Most Impressive Game AI?

togelius asks: "I have the feeling that when developers make the effort to put really sophisticated AI into a game, gamers frequently just don't notice (see e.g. Forza). Conversely, games that are lauded for their fantastic AI are sometimes based on very simple algorithms (e.g. Halo 1). For someone who wants to apply AI to games, it is very interesting to know what AI is really appreciated. What is the most impressive game AI you have come across? Have you ever encountered a situation where it really felt like the computer-controlled opponents were really thinking?"

Comments

no

[flynt]

Have you ever encountered a situation where it really felt like the computer-controlled opponents were really thinking?

No, but I've rarely encountered games where it feels like my human opponents are really thinking, either.

Come off as cheap

[Romancer]

A lot of AI that is used in games today can come off as cheap since the computer can think and compare much faster than a human player. Imagine fighting an opponent that can react 10X faster than you.

Another way to look at it is if you think that the AI is learning patterns and adjusting for tactics.
That's been played out in many genres, the most recent to come to mind is the Stargate SG1 episode where a character must face a situation that adapts to his efforts and becomes impossible to beat since the game can react faster than he can and has a perfect memory.

It's a ballance that game AI must match, playability and difficulty.

Re:Come off as cheap

[Romancer]

That should have been RE-Playability. as in how many times you can beat the game and still pick it up a month later and be challenged by the new situations.

Re:Come off as cheap

[CastrTroy]

Games have gotten a lot better. I remember in the original Mortal Kombat, you could get to the dual-character matches simply by picking scorpion and pushing back,back,punch for the harpoon, followed by down+punch for uppercut continuously for the entire fight. Games have gotten a lot better at not letting you do the same thing over and over again. However, I have yet to find a hockey game that doesn't have a "trick" that lets you score about 30 points in a game. the trick seems to change from year to year, sometimes it's the wrap around, sometimes the one-timer, but there is always a trick.

Re:Come off as cheap

[mgiuca]

That's why the "best" game AI isn't necessarily the smartest or most responsive - it's the most human.

Writing an AI that makes the occasional "human error", or responds in a reasonable time is harder than writing the "best AI possible", but makes for a more believable (and of course, enjoyable (since who likes getting beaten all the time)) game experience.

Re:Come off as cheap

[Romancer]

Exactly.

The most human AI would see patterns and adapt. The learning also plays a role, since just randomly playing out pre-programmed moves till one works leads to repetitive gameplay. The AI must have a very low level of options to piece together so it can make larger combinations that turn into tactics. The smaller each action is and the more actions it has to work with will let it find the best action. But that still doesn't mean that it has learned anything if it starts over with each situation. It has to have some sort of loose pattern recognition to see similar situations and apply the most likely solution.

Add all these things to an ability to totally screw up and you'd have a good AI. :)

Re:Come off as cheap

[2short]

Targeting by calculating from internal data and perfect knowledge of the physics model, rather than analyzing screen output, is not what I would typically call "AI". Not all games are First Person Shooters, and FPS are not particularly good tests of AI since targeting is such a big part of them.

In simple, pure-strategy board games like Chess, the best AIs are only on par with the best humans. In more complex mostly-strategy games, like the various Real Time Strategy games, the AIs are hopelessly outmatched, and the difficulty of player-vs-computer scenarios is typically adjusted by how huge a head start the computer is given, or how much it is allowed to cheat in various ways.

Fact or fable?

[lawpoop]

When I was contemplating learning video game programming, I was reading a guide that told you first to program a pong clone, and then a pac-man clone. Why pac-man? It teaches you AI. The ghost behavior is actually fairly complex. One ghost wanders randomly, another tries to get on the opposite side of the board from wherever pac-man is. The other two form a hunting pair: one tries to cut off your escape while the other goes for the kill.

I never thought that the ghosts would be so complex!

Re:Fact or fable?

[EGSonikku]

And they aren't...at least not until Ms. Pacman. In the original Pac Man the Ghosts followed very predictable patterns which they never changed, and it is quite common to simply memorize these patterns and play the game with your eyes closed.

http://www.mameworld.net/pacman/patterns.html

Re:Fact or fable?

[FuriousBalancing]

Clever girl.

Re:Fact or fable?

[Threni]

To be fair, the fact that patterns work simply means the AI is deterministic. Pacman could have extremely complicated AI but if there's no learning from a players past, random elements etc you're always going to be able to learn to find a patten which works.

To be honest, I've always thought that AI in computer games sucked. Games are usually made hard by having the bad guys have better fire power, shields, energy etc than you, or having loads of them against one player. It would have been a laugh, for example, to have a doom style game with one player against one computer bad guy, but have him be as smart as a human. Thankfully, online multiplayer games mean you are no longer restricted to whatever crap AI system the programmers manage to string together, although the problem has now shifted to dealing with people cheat - a problem which games programmers show no signs of being any less inept at dealing with than with AI.

Re:Fact or fable?

[lawpoop]

This post seems to contradict your information:

"AI : We wanted to integrate in our game the original AI behavior of the ghosts (those that were in the original Pacman game). Without AI, the game was not interesting to play, since a random behavior is too simple to play. Each ghost has its own personality: Shadow is the red ghost and it chases Pacman all the time, using a straight forward tracking algorithm. Speedy is the pink ghost. It is very fast but moves in a random manner. Bashful is the blue ghost: it is shy at the beginning and escapes from pacman all the time, but if Pacman approaches him to much, then it is not shy anymore and begins to chase him (Pacman is then chased by two ghosts at the same time...). Pokey is the orange ghost and is slow and moves in a random manner. "

Not as complex as the story that I read, but apparently they don't follow a pre-planned course.

Civilization III

[Brandybuck]

Civilization III. It's uncanny how it makes you think the game is outright cheating.

Re:Civilization III

[Pyrrhic Diarrhea]

That's because it *is* cheating. The hole in my wall next to my computer can attest to this well established fact. :)

Re:Civilization III

[Taelron]

All of the Sid Meirs Civilization games cheat. To prove it, get one of the trainer and save game editors. Save the game each round and look at the the AI players citys and units. They will produce two units at once and instantly without spending money to "buy" them. The cities dont suffer ill effects of to many troops or to long of a war. The higher the level you set the game at the more the AI cheats.

Galactic Civilizations 2

[Zarhan]

Well, one of the greatest experiences (And still is), AI wise, is Stardocks XXXX-type space strategy game, Galactic Civilizations 2. I especially like, when on easier levels, you do something, and the AI race sends a message "It seems that you are making a massive buildup for war. However, with this difficulty level, I pretend not no notice it until you actually make your strike." or something to that effect.

Simplfy the game and the AI gets better

[kinglink]

The Best AIs I've found are in some games like Yu-gi-oh the card game I'm currently working on nightmare troubadour and most of the opponents I've played always make a "great" move. On the other hand there's a couple opponents who are dumb as bricks, yet these enemies are suppose to be dumb as bricks (they are first time players in the story) And it's amazing how poorly they play (the play "well" for stupid AI, but they make bonehead moves that a new player can easily capitialize on. The player feels like each player has a different style, not just a different deck, and that makes for a much better game. (this is coming from a 25 year old guy in the game business).

The reason it's great is that there's simple rules to the game that the AI can know. There's been one point in the game where the AI got confused mainly because I blocked her in with a couple traps, but overall the Ai's abilities in the game are outstanding.

The important think to know about AI in games is it's not "AI". It's scripts or code that simulates scripts. There's no neural nets or anything else because we can't get the power for a neural net in an active game. In chess we can but then chess no longer is fun unless we tone down the "intellegence".

Some other great AIs are Gears of War (On insane they do great flanking maneuvers and such) Ghost recon (they really seem to know how to take cover and make it a challenge for the player to take them out. however the friendly AI leaves.... alot to be desired), Oblivion (watching random people walk around is pretty impressive, it helped build up that game.) and others, but there's none that make me think I'm fighting a real person.

There is a push to create truer "AIs" in games, Gran turismo created a way to train Drivers, Forza 2 is improving on it's drivtar system, Virtua fighter 4 had a way to teach an AI fighter, which was cool and indepth. But these are all "Scripts" taken from player experiences, not exactly AI. There's other games working on "true AI" but even then it's still toned down because we don't have the tools to make the driver "think" yet. It's just rail following and teaching the computer how to follow rails or when to break away from them.

I wouldn't say the molyeniux's games had great AI but they have good AI that at least learns a bit. Yet they feel like it's all you telling the game what to do, and it trying to figure out what you want it to do (and it fails) where as the Sims has interesting AI, but never feels real (mainly because the game never feels real).

So overall if you want to see good AI, look at simple games, expecting full 3d world simulations to have great ai is still a long way off but it's slowly coming. However this push for "graphics graphics graphics" won't help AI in the long run, but hopefully in a couple generations we stop worrying about graphics and work on AI and physics which seem to be more beneficial to the player then higher polycounts.

Re:Simplfy the game and the AI gets better

[pescadero]

The important think to know about AI in games is it's not "AI". It's scripts or code that simulates scripts. There's no neural nets or anything else because we can't get the power for a neural net in an active game. In chess we can but then chess no longer is fun unless we tone down the "intellegence".

Hmmm. If I write a neural net program, how is that different than what you call "scripts or code"? It's still just code.

And the best chess algorithms (which you seem to claim are "real AI") are just search algorithms that search 30 moves into the future (with pruning)

You're making a distinction between "real AI" and "not real AI", when really there is no distinction. If a system can solve a problem intelligently then it's AI, regardless of the algorithm.

There *is* a distinction between "human-like AI" (neural nets) and other kinds of AI, but we'd be foolish to assume that human-like intelligence is the only kind of intelligence.

Re:Simplfy the game and the AI gets better

[kinglink]

If we are talking about a computer game I'm hoping we are talking about human-like intelligence.

What I really was trying to get across was a common misconception (one that stuck me when I got into a game company) that "AI" as it's taught in school is very different hen AI as it applies to most games. The biggest difference is most AIs don't learn, and most are pretty much just a script that doesn't change. We don't have the ability to throw away any cycles of the game so the AI tends to be highly stripped down to the point it's just "oh I see a gun, I'm going to react to the gun, how should I react to the gun, I'll do that." This is completely scripted to the point where you can tell what's going to happen if you point the gun at the person a second time or a third time. There's no "thought" or "intelligence" to the system, thought it might seem "intelligent"

A chess AI on the other hand evaluates all the options of what it can do and chooses a best option, the pruning is a form of "thought". A chess master will be doing something similar where he thinks of all his possible moves and then considers responses and so on which is effectively using game theory. To me that's actual intelligence even if it's not fancy.

The difference between a neural net program is it's code that tries to simulate the learning and thought process if you will, the code that AI in games use is just like I illustrated above. There's an "action" and the code quickly decides what's the reaction and does it. It doesn't try to evaluate too much because we don't have the cycles to do that.

Re:Simplfy the game and the AI gets better

[daffmeister]

Actually chess masters don't evaluate every move and every counter move in the manner that a computer program does. A lot of their analysis is based on familiar patterns, recognising promising lines by this method.

Witness Kramnik's missing of a mate-in-one in the recent match against Deep Fritz. It was such an unusual pattern (opposing knight on the eighth rank) that he just completely missed it.

Chess programs are much more about brute force. They've got so good at brute force that it looks pretty intelligent now.

Re:Simplfy the game and the AI gets better

[tmortn]

Eh, the chess programs are mostly just pattern matching against libraries of stored games and brute force projection of all possible moves from a given point. They rank the options and the top option always wins. I suppose when considering that the computer is storing your games (ie growing its library) then its responses could change over time. Not because it learned, but because the same 'intelligence' is applied to a different data set. Given the same data set the ranking system will always react the same way in the same circumstances. A very rudimentary form of 'learning'. Really it isn't learning any more than say the Pythagorean theorem which also gives different results based on different inputs despite the fact its method does not change.

I can't say I buy your neural net deal either. At least not as a distinction between 'real' and 'non-real'. Will certainly agree in your examples there is a distinct split between computationally expensive and computationally cheap ways of determining courses of action for a computer program. But no "real" AI exists yet, that is no Turing test capable AI... neural nets or no neural nets. I think the point the other response was trying to point out is that regardless of the method used to simulate intelligence (static script vs adaptive code) the important factor in determining if something is actually artificially intelligent is generally agreed to be the Turing test. That is in interaction with humans it is impossible for a human to distinguish if the responses of the machine are from a human or not.

Frankly, 'real' AI from something like neural net code is not something game companies desire at all (computationally expensive or not). The problem is such code is by its nature un-predictable because any such system of learning/mutation has to be based on the unpredictable input of the player. A game which is unpredictable is bad from an investment standpoint because you don't know what it will do or how it will respond. Thus deterministic scripts that can be relied upon to act in a consistent way beneficial to the game are generally far more desirable. Not to say I don't want to see it come to be... just that the likely hood of seeing serious work along these lines is pretty slim right now barring some kind of breakthrough.

Counter-Strike AI

[Foo2rama]

I am constantly amazed at how bad the AI is in this game, after years and years of developement you would think that the Ai would have developed alittle more. While very advanced in speech capabilities, the AI relies on taunting you by claiming you are a noob, cheater, or a camping f**ktard, and will even call you GAY. In game play the AI is still weak and just does the same thing over and over again, and will constantly be baited into sticking its head around a corner, or runs into flashbang grenades on a very regular basis, failing to learn from its past and how it got owned over and over. Finally the AI deems you are a cheater and runs to load another AI called an Admin that will ban you because it cannot understand how you are so much better then it.

Friendly AI

[nmb3000]

Personally, while enemy AI is something that's pretty neat to see in action, it's the friendly AI that gets my attention. Most games seem to put all their effort into the enemy, while you friends turn out to be schizophrenics with an IQ of about 40. I haven't played, but I have heard that something that people complained about in Gears of War was was the poor team AI.

I don't play many games any more, but Halo 2 was one that I thought pulled ahead of the pack a bit. Friends that can drive vehicles was pretty cool (albeit not always the safest drivers...) allowing you to man the gun in the back. They also seem better at not running right in front of you when you're in the middle of launching a rocket, and also do little things like take advantage of available cover (or in other cases jumping up on top of said cover and getting blown to bits). Halo 3 is supposed to have even better AI for both friendlies and enemies, and that's one of the things about it I'm looking forward to.

Warcraft III (Insane!)

[nartz]

The best AI I have seen is probably in WC3. However, I feel that in many games, it isn't the AI that is good, but rather that the computer players sort of cheat by having knowledge of everything in their environment; for example, they know (from the beginning) where the bases of other players are, instead of having to search like a human player. This gives them a huge edge - think of it as a human player playing against another with a map-hack, very unfair.

Wesnoth

[Glowing Fish]

I would have to say that the AI for Wesnoth, an open-source Turn Based Strategy, is one of the better AIs I have encountered (for that genre of games).
Although it isn't that the AI is that well done, it is that the rule set is simple enough that an AI can follow it.
I've played Civilization, Heroes of Might and Magic and Masters of Orion, the trinity of TBS games. Although they were often very good, the AI could only win in all of them due to "cheating" of a sort. The reason was that the various different factors to be considered were behind the planning ability of an AI. For example, in Heroes of Might and Magic II, there were seven different resources that a player could collect. Often, towards the end of the game, even while it was badly losing, the AI would be running around trying to grab resources, and would lose because of it. In Civilization II, because there was so many different units and improvements to be built, the AI would produce useless units, or spend all their time building improvements to cities that were about to be captured. The algorithm for keeping track of so many factors is impossible to make in an AI. AIs can't understand what is relevant and what is not.

So, in Wesnoth, there is only one resource to be considered, gold. Damage is also a straightforward mathematical calculation. So with the simpler rule set, the AI can play in a relevant way. Not that the rule set is simple in the sense of easy, it has a few factors, but those few factors can be combined in intricate ways.

So Wesnoth has one of the better AIs in my view, although of course it can still be tricked and worked around, but then any AI can be.

Cheating

[dunezone]

Ive noticed that AI is not designed to beat your next move but is designed to cheat you without the player noticing. Command and Conquer and Gears of War are two games that have two well hidden cheats. Command and Conquer is twelve years old almost, the enemy AI was programmed to always have full resources as long as one harvester made it back. Therefor what would take you five harvesters would only require them one. Most players would of never noticed this unless their strategy was to cut off enemy resources instead of an full out assault. Gears of War was praised for having AI that used the environment to their advantage which helped cover a little cheat they had. The AI had a weird tendency to know exactly where you were as long as your cross hair covered them or came close to them. For example if you were to pop your head out and just happen to have your cross hair on an enemy turret that was always firing at a covered friend, it would immediately start firing at you, this would also goes for the regular grunts/guards. This is very noticeable on "Insane", since that mode requires you to use cover 90% of the time and better tactics then rush in and shoot everything that moves. AI is not designed to outsmart/out think/or consider your next move, in my opinion most AI is designed to defeat you by using small cheats in the programming that give it an unfair advantage and hopefully designed so that you wont be able to notice it.

Good, or good for the price?

[Pode]

GalCiv II has given me the worst beatings I've ever taken in a strategy game. Shogun: Total War managed to spring a tactical ambush on me once (although in fairness my grip on tactics was much worse back then). Both of those AIs gave me a challenging game experience as a player, which is what "good" AI should be judged by.
However, if we're talking about "impressive" AI, nothing I've seen in the gaming world can compete with Paradox's EUIII. Yeah, I know, each individual AI nation makes a lot of bonheaded moves. But the game is managing the armies, navies, economic, religious, colonial and foreign policies of up to 300 nations, every game day when a game year can go by in a minute or two, on a 1.9GHz processor. Considering the number of cycles and the amount of memory avaiable for each AI opponent, it's simply amazing to me. I really think that should be the basis of comparison, not so much the level of play the AI achieves, but the level of play it achieves with the resources available to each AI player. If nothing else, that standard makes it meaningful to compare old games against new ones.

Re:Kart Racing

[Spazntwich]

I'm just glad I'm not the only person Mario Kart's cheating AI infuriated.

Back in my greener days, I lost a few SNES controllers to a perfectly tossed egg from Yoshi on Rainbow road. That motherfucker.

F.E.A.R

[alphaseven]

Here's a short article on the A.I. in the game F.E.A.R., "F.E.A.R.'s AI Demystified", (in more detail here). Having played through F.E.A.R., what impressed me so much was that a lot of what is called A.I. is actually audio and animation. You can make enemies seem way more intelligent than they really are by doing stuff like have detailed animations for stuff like hopping over barriers or diving through windows that's triggered when they are in certain spots. They would also have the enemies shout stuff, if you had your flashlight on they would scream "Flashlight" and dive for cover.

Re:ummm, Galactic Civilizations II?

[PresidentEnder]

Galciv 2 certainly gets a huge vote from me, because the AI did beat the crap out of me, repeatedly. However, the AI does have the advantage of being able to accurately micromanage every planet every turn to produce the best combination of production, research, and cashflow.

I'm also very impressed with the AI in the original galactic civilizations. It does cheat at the higher levels, but up until that point (I think normal mode doesn't cheat either way) it's very impressive and it really does feel like the AI is thinking. More impressive is the fact that each major race has its own AI: not customized by arguments in the race, but specific, independent C++ code telling them what to do, written from scratch.

Screw game AI

[SharpFang]

Google Maps AI rules.
See point 23

yes, in GalCiv2

[x_codingmonkey_x]

If you want a really challenging AI, and one of the best I've seen around, I highly recommend Galactic Civilizations 2. It's a 4X game similar to Civilization but takes place in space. The developers frequently post articles about the AI and how they are continuing to improve it. Furthermore, they read user's strategies and then improve the AI. The greatest part is that on the Tough setting (highest difficulty before they start giving the AI bonuses), the AI provides a challenging game. This is unlike most AIs where a "challenging" AI essentially means that it has a 200% economy bonus. Interestingly, the AI adapts to your game play and they have talked about using the second core in dual core processors to analyze previous games and use different tactics to counter known strategies.

Re:ummm, Galactic Civilizations II?

[Edmund Blackadder]

I agree, GalCiv II certainly has a very tough AI.

Another very good one is freeciv. Freeciv may look much cheesier than the regular civilizations but in AI it surpasses it by far. I suppose it helps that it is developed by players of the game.

Game where computer seems like it is thinking

[Brian_Ellenberger]

Galactic Civilization I and II (see: http://www.galciv2.com/) is one of the few games I have ever played where it seemed like the computer was thinking. If you have never played GalCiv, and you like strategy, I highly recommend picking them up. I consider them to be superior even to the Civilization series. Brad Wardell prides himself on the AI, and it definitely shows. The computer is very difficult to beat and does not cheat. It actually responds in a logical manner, which makes GalCiv go from just being a number-crunching exercise to an actual strategy game. For example, when making some "aggressive" moves towards an enemy (moving some attack ships to an "ally" to wipe them out) I've actually had the game pop up a message from my ally (before ever entering his space) saying something to the effect of "I used to play video games when I was a kid, and when I did I used to build my forces up and send them to sneak attack an opponent. Well I am no video game." Other things like the fact that if another civilization is dependent on you for a large amount of trade income, they won't just randomly attack you because it would hurt them too.

Re:Game where computer seems like it is thinking

[Tablizer]

Other things like the fact that if another civilization is dependent on you for a large amount of trade income, they won't just randomly attack you because it would hurt them too.

That AI is smarter than most Earth leaders.

Re:Game where computer seems like it is thinking

[Kingrames]

90% of the time when it seems like the computer is smart, it's more because the game and the AI merge well together.

If the game has lots of bugs, bugs you might not normally see, the AI will suffer.

Oftentimes the A.I. of the game doesn't make the computer smarter. Making a game that's smooth and supports a good A.I., however, will make a much bigger difference.

With a game like chess, the A.I. program is huge and immensely sophisticated.
With a game like tic-tac-toe, you can make an A.I. that can't be beaten, simply because the game is simple and allows for that.

It's important to keep in mind that the actual A.I. algorithm can only accomplish so much. Putting Deep Blue into the seat of your tic-tac-toe opponent gives you the same result as the program you wrote that doesn't break a page.

That being said, a few more examples to look for for good A.I. that merges well with its game would be Kohan and Kohan 2. The AI in that game blew me away.

For an older game, check out emperor of the fading suns (you can get the full game for free) http://free-game-downloads.mosw.com/abandonware/pc /strategy_games/games_e_f/emperor_of_the_fading_su ns.html
I still have fun playing this one. It's interesting how the computer will actually send you money for nothing in the interest of making you like them more. There are a few other subtle details.

Incidentally I've heard that Gal Civ is based off of EFS, so if you haven't had a chance to check it out, enjoy.

Re:Game where computer seems like it is thinking

[beckerist]

Oddly enough...you're dead on.

When programming AI it's much more about pandering to human error than emulating perfection. Anyone could write an algorithm that reads in the user input, and knows exactly how to react to kick your ass. It's extremely difficult to write code that gives the user just a tiny edge. 100% impossible is very easy to write for. 95% improbable is not.

Re:Game where computer seems like it is thinking

[greenkite71]

IIRC, chess is just search (usually Alpha-Beta pruning) of a state space with some function giving the "value" of each state. Conceptually, chess AI is very simple, although I suppose the evaluation functions have become slightly more complex over time, but I'd hardly call the programs "huge and immensely sophisticated." Chess AI has gotten better largely because faster computers can search more of the state space over a given interval.

The original

[Squalish]

Unreal Tournament.

It had the first bots that you could play against for hours and not even notice you were offline. I havn't encountered a more convincingly human AI in the dozen FPS games I've played since, including UT 2k3(which probably means that the UT maps were just easier to code for).

It's the only game where you can feel yourself increasing in skill over the course of a few days of playtime, and ratchet up the difficulty a bit and get the same kill ratio, without feeling suddenly overwhelmed by perfectly aimed headshots.

Civilization IV

[Kuciwalker]

With Blake's http://apolyton.net/forums/showthread.php?s=&threa did=159157A Better AI which Firaxis actually included in the latest patch, it's gotten pretty impressive.

Perfect Dark N64

[oliphaunt]

OK, it's pretty old by now, but I was a big fan of Perfect Dark. The AI robots had difficulty settings AND personalities. If you were running deathmatch games against the AI, you could set AI's to have various behavior attributes:

• PeaceSim:As the name implies, this Sim hates violence. In fact, the PeaceSim will go around hoarding weapons so people don't pick them up, and disarm people for their weapons. Therefore, they'll drop a payload of weapons when you kill them. Just don't let them sneak up on you...
• ShieldSim:Like some human players I know, this Sim is a shield addict. It will always go for the shield, even if it has no weapons! In fact, if you damage its shield in the least bit, it will retreat to get another shield! My advice is don't let it.
• RocketSim:This is the pyromaniac of the Simulants! The RocketSim will always pursue the explosive weapons, and will set them off, even if doing so would spell death for itself! Avoid this Sim, or kill it before it can get an explosive.
• KazeSim:This is fearless, suicidal menace. It will make suicidal runs, even with no weapons, to try and destroy you. It fears nothing, and that makes it a dangerous enemy.
• FistSim: Unlike the PeaceSim, the FistSim is violent. Like the PeaceSim, though, it will hoard weapons and try to engage you in hand-to-hand combat. It won't use weapons, but it will do good damage with its hands.
• PreySim: This Sim truly feels that honor is a minor detail in a fight to the death. The PreySim dislikes competition, so it will hunt down the easiest targets to gain an easy kill. Its favorite targets include weakened opponents that are unarmed or armed with a weak weapon, and enemies that have just spawned. The PreySim also loves to cloak, so beware.
• CowardSim: This is the SimWussy. It flees to safety at the mere sign of confrontation, and will only confront you if it has a superior weapon. Carry a big gun, and you will rarely meet this Sim. Hide out and try to catch the coward off its guard.
• FeudSim: Stay out of this Sim's way! If the FeudSim goes after you, it will hunt you until the end of the game! It will mercilessly hunt its target, even if you kill it.
• SpeedSim: As the name suggests, this Sim is extremely fast. It's definitely faster than you, so it's difficult to hit with standard weaponry. It's impossible to flee, so stand and fight like a man.
• TurtleSim: This Sim is the opposite of the SpeedSim. It moves at a much slower rate than most players, but it has a shield that is twice as strong as the standard shield! Fortunately for you, it has restricted mobility due to its shield.
• VengeSim: This is a psychopathic Sim! This Sim will completely ignore other players just to attack the player that last killed it! It attacks with a vicious rage; so to avoid its rage, just leave it alone.
• JudgeSim: This is the only decent Sim. The JudgeSim acts like the judge of the battlefield, going after the winning player to even out the odds. That means if you are an expert playing against some young rookies, expect this Sim to come after you!

The variety of personalities gave the game infinite multiplayer replay value, and made it easer for beginners to get into the game. You could pick simulants that would ingore a newbie human player and attack only the players with more kills, so the good players can run around slaughtering AI's on the difficult setting in the same game that a newbie is just exploring the level and figuring out how to reload. The experts still have fun while the newbies don't get instantly killed every time they spawn.

Re:games don't really need good AI

[eebra82]

AI has nothing to do with difficulty. It has to do with realism, that you picture the opponents as real people and things that behave accordingly.

Creating difficult opponents is just a matter of reaction and aim. They can just stand blatantly still and fire at the very nanosecond you reveal yourself.

Good AI is the kind that retreats when it is outnumbered, interacts with its comrades and the surroundings, explores and interacts with the mess that you yourself may create and so forth.

Falcon 3

[Ullteppe]

Anybody remember Falcon 3? While all the other sims pretty much had scripted missions (many still do), Falcon tried to run the whole war in the background. And when you ran into other planes, they acted pretty convincingly. They were hard to beat as well, I remember the Mirage F1s especially as being pretty tough in a dogfight. Pilots of different planes acted differently according to their planes strength/weaknesses. They used 6 months to patch the game sufficiently that it didn't crash all the time, kind of understandable with the complexity.

It has got to be the original Alien vs Predator

[SmallFurryCreature]

The game was not perfect, its crap save system for one thing BUT playing as the alien had some nice moves.

For once the "enemy" was more then just cannon fodder with a deathwish. You were a nasty scary alien and the humans knew it. So a fair number of them would NOT react all that well to signs of your presence.

Once I was hanging upside down from the ceiling slowly eleminating the lights. Below me a civilian must have spotted something for he threw up a molotov cocktail (or similar) at the shadows. Offcourse gravity did its job and it exploded when it fell down again and engulfed a soldier and another civie.

Another event had me again on the ceiling staring around corner down a hallway that was sloping down. At the end a soldier with a rocket launcher must have spotted me for he fired a round. Pity that a bend in the tunnel was in the way and the rocket exploded just a few meters away from him. AvP had volumetirc flames but by the time it reached me I had already ducked back into hiding.

Other events saw soldiers machine gunning straight to civilians as they tracked me and scared people hiding in toilets and throwing grenades in confined spaces.

In itself stupid behaviour every last one of them BUT made realistic because of the fact that the AI acted as if it was scared.

If it had been a regular soldier fps the AI would have blown chuncks, but because you were a scary nasty meany alien chewing the head of humans, the AI worked.

The combination of soldiers tracking you down combined with the capacity to introduce a state of mindless terror really worked. AI makes a dumbhead move? Must be because you scared it senseless.

Pity the sequel lost all of the originals capacity.

A really great AI must make you believe you are part of a real world.

I know the best AI ever!

[guruevi]

It's my manager's; Basically his algorithm is to listen to what I have to say, deny my ideas or find a situation where an exception would be generated and then depending on the number and level of participants, introduce my idea as his. I tell you, that shows great intelligence to his overlords although it's artificially generated but the actual participants start to get it after a few times.

Re:Kart Racing

[Cecil]

It's not a star, not the same way you get a star from a question block. It's an invincibility special ability. It's not quite the same as a regular star as it doesn't make you go faster, improve your handling, or allow you to drive with reduced penalty on grass/mud. It's just invincibilty + collision damage.

All of the AI players have their own special abilities, which fall into two basic categories. Mario and Luigi get invincibility, everyone else gets a tossable/droppable item (Banana, Fireball, Shell, etc) which they can use repeatedly.

It's not the same kind of cheating when a car mysteriously catches up to you at seemingly supersonic speed. In the former case, it's an obvious game mechanic. In the latter case, they're trying to be subtle about it and use it to cover up AI weakness, hopefully without you realizing that they're doing it.

Re:Perceived Intelligence - Simple is better?

[Eivind]

That's typical of the AI possible today: It can't actually perform better than a stupid program following simple rules.

Had a similar depressing experience in my class on AI. The task was to build a neural network that could guesstimate the sex of a first-name. A quite complex neural net, trained on 300 random male and female names could thereafter guess the correct sex of a name about 65% of the time.

Which seemed impressive until someone pointed out that a trivial table-lookup of the most common 100 female and male names, and random guesses for everything else is enough to reach about 70-80% (depending on the country the names are from, some countries have more variation than others) and even something as simple as "if ends in a, guess female, otherwise guess male" is enough to reach similar "accuracy" as the neural net.

Best game AI?

[TheCreeep]

Ask Kasparov...

Re:The toughest AI I've ever played against...

[yoink23]

Nice work, Ender.

Re:ummm, Galactic Civilizations II?

[ditoa]

I just went to the GalCiv2 website to have a read and saw this

No CD copy protection. Once you install, you never need your CD again. You can even use the included serial # to re-download the entire game from us years from now.

That is very refreshing to see these days. I have given up on most PC games these days because of their copy protection systems.

Re:ummm, Galactic Civilizations II?

[bcmm]

I've seen some fun glitches though. The best was persuading an AI player with no capitol city to give ALL of his cities in return for a lot of technology.

Re:Perceived Intelligence - Simple is better?

[NekoXP]

AI in games is mostly triggers and actions.

It's still AI if those triggers are hardcoded or based on statistical analysis.

It *is* intelligent for an NPC to realise a grenade was thrown by the player into it's general area, and throw it back at the player. That's not to say it shouldn't be ranked highly or that it is a crappy AI.

If an enemy hops over a wall next to him for cover it's the enemy realising that he needs cover and there is an easily hoppable wall. He could just as well duck behind a barrel, but the barrel may be made of soft shitty wood, the wall is nice and made of brick. It makes an education decision just like we do. They may well be SCRIPTED.. if near wall hop over wall else if near barrel duck under barrel else if player is actually in effective firing range, run the hell away else sit there and taunt them into the minefield..

Think of your thought process when you would be in the firing line and you have the choice between ducking behind a worm-riddled barrel to avoid gunfire, or a solid brick wall that you can hop over. How many seconds does it take? Can you remember every microdecision you made? No, you think "ohshit I'm being shot at" and probably duck behind the barrel under stress, when it starts to splinter then you scramble over the wall and realise you dropped your gun hopping over the wall..

Does that make it crappy AI that it did not break out scientific analysis of the situation and count variables or do complex physics?

Re:ummm, Galactic Civilizations II?

[Anonymous Coward]

I don't know where you're getting that bullshit from, but it's completely untrue. You don't even have to enter the CD key unless you want to download updates.

The Thief Series was Groundbreaking

[BrendaEM]

The AI could see not only see in a view fustrum, but also by how much light you were lit by. The AI could hear depending on what surface you walked on, you could affect the light by putting out torches, affect the sound my mossing the floor. The AI notice bodies and things out of place, such as a climbing rope. The AI also had different alert states. I think that they are pretty good for a game made almost a decade ago.

There are over 400 Thief series fan missions. Last night, I played "Ominous Bequest"
http://southquarter.com/?p=131
One level change for 6 hours of gameplay! Yes, Thief 1 and 2 graphics are quite dated, and low-poly, but if you can forgive that, the gameplay and atmosphere compensates for it.

Lately, there's been a reinsurance in Thief 1 and 2 add-on missions. There's a updated version of 680mb Thief2X add on. Missions like "Ashen Age," and a "Night in Rocksburg" have breathed a little life into T2 visually.
http://forums.eidosgames.com/showthread.php?t=5526 3
http://southquarter.com/?p=131

Someone is working to refresh the Thief Series Engine, but the source code would help. I wish that Eidos would release the source code--for an eight year old game.
http://www.ttlg.com/forums/showthread.php?t=102289 &page=11

Re:What is AI?

[LighterShadeOfBlack]

Well no, of course nothing in any existing game (or anything existing period I guess) is close to true artificial intelligence in the larger sense of the term. For the context of gaming I think it's fair to say everyone knows we're talking about creating the illusion of intelligence within the bounds of gameplay.

S.T.A.L.K.E.R

[Eesu]

Been watching it for 3 years at least, originally its AI was going to be groundbreaking. After getting the game last week, and playing/beating it, the AI was indeed SUPERB, but not groundbreaking. However It is the best AI that I've ever faced. As a group of enemies slowly move from covered position to covered position and outflank me to get a shot, always keeping their heads JUST above say the ridge of a hill to give me the smallest target possible, ducking back behind cover to reload, crouching and walking slowly when trying to be sneaky. It was truly outstanding AI and I Appreciated the hell out of it.

Far Cry

[lewp]

Far Cry has great AI. I don't remember ever going "zomfg the computar is thinking!!!", but the enemies respond in a sensible, coordinated manner -- sweeping areas where disturbances are heard, covering each other, and using weapons intelligently. Far superior to Half-Life (and, credit where credit is due, several years after Half-Life), but also in a much more open-ended game world, where the mobs don't just have to navigate a room full of crates.

The really sad part was when, halfway through the game, they switched from "smart" soldiers, to Doom-esque mutants who just ran straight at you. Ruined that game for me.

Operation Flashpoint

[grumbel]

Operation Flashpoint is among the most impressive games that I have seen when it comes to AI, not necessarily because its the most sophisticated, but because the AI has a very noticeable impact on the gameplay.

No matter how often you replay a mission, it will always come out totally different. This comes in large part from the very open nature of the game, namely there are basically no rooms, its all just one huge outdoor environment and both you and the enemies can go basically wherever they want. It also comes from the way the missions are designed, there are no soldiers that jump out from behind a rock to shoot at you, instead the enemy soliders just follow their routine, they walk their paths, drive a convoy along the road or whatever they have to do right now. Thanks to the large area, they don't have to walk on a stupid 10 meter long path and then turn around to repeat it over and over again. This all leads to a very realistic feel, because all the limits of classic FPSs are removed. Its also not you against 100 other, but often more like you + 5 team members against 10 other, so its a much more even match. In Operation Flashpoint the player is also completly equal to the enemy, one good targeted shot and you are dead, no 100% health that slowly goes done while enemies die on the first hit.

Another aspect that is noticeable in Flashpoint is that there is a very clear difference between the state of the enemies, you can easily tell when they are on patrol, when they are attacking you and when they are searching for you. If you shoot at them they will notice it and react appropriately, this also makes it easy to tell when they don't notice you, i.e. you can hide rather well, a tank won't see you when you are crawling directly infront of it, etc. As a player its simply easy to tell what the enemy is currently doing, since the animations and behaviors are rather distinct for each of the actions.

Last not least Flashpoint is also a game where you need your teammates and where they are not just stupid cannon fodder. Most of the time your teammates can take very well care of themself and you don't have to babysit them like in some other games (HalfLife2...).

All that said, the AI in Flashpoint is far from flawless, it can often be a nightmare to get your group to mount a vehicle or get to a certain point, they will do what you want, but when they crawl around for a minute before entering the vehicle it can get pretty annoying. But overall Flashpoint really is among the best, it is however not just the AI itself that does the job, but the overall game design that threads players and enemies basically the same, it also helps a lot that the whole gameworld is interactive, if you see a tank, then you can drive it, there are no artificial barriers, no pre-scripted events that happen outside of normal gameplay rules. That scripting that is there blends perfectly into the normal gameplay.

Re:What is AI?

[timelorde]

Unless, of course, if you're developing Vogon Universalis

Re:Actually, I really hate this

[vux984]

There was a game, Warzone 2100, that was absolutely brilliant in this regard. Not because the AI didn't do this, but because the player COULD. Not to the same level as the AI, but enough to give one an awesome sense of power over the battles.

Key features in that game:

Ctrl-click/double-click/box selection, and assignment of keyboard shortcuts (stuff we're familiar with in all games)

The ability to set postures like do or die, retreat at half damage, retreat at 3/4 damage etc (again familiar stuff)

Repair facilities - buildings that would repair nearby units - but with a twist. Vehicles set to retreat at X damage would retreat to the nearest repair facility instead of just going back to base and sitting there.

Mobile repair vehicles that automatically sought out and repaired nearby damaged units

Build Order chaining - you could give your construction vehicles orders to build a barracks, then a missile silo, then a factory, then a wall.

Target chaining. You could give a battle group a series of targets that it would attack. Commonly in these games we want to concentrate firepower, and this makes that happen.

Battle field production - you can actually order new units be produced at any of your factories anywhere from the front lines.

Target designation units for airstrikes, and artillery bombardment, as well as 'counter target designation units'. For example, you can assign your aircraft to a designator tank unit. Then whatever that tank targets becomes the target of all the aircraft assigned to it. They'll fly in, fire off their munitions, return to base to refuel/reload, and then fly back...

Or, for example, if you have a counter designator in an area taking artillery fire, the artillery guns in your base will automatically fire back on the source of that fire, if they're in range. (and those guns have AMAZING range.)

General units - this is the ultimate innovation. These units form the focal point of your armies.

Generals are hard very tough to kill units with a long range targeting laser. They have dedicated gui features to select and cycle between them. Units assigned to the general go where the general goes. Whatever they paint the units assigned to them attack. So...

Naturally you can link units to your generals.

You can move a diverse battle group without having to setup keyboard shortcuts, box selection, etc. This comes in handy, because it frees your keyboard shortcuts for other tasks. And units don't get left behind.

You can order that diverse battle group to attack a target, or series of targets.

You can link factory production directly to generals. (And built units automatically join the battle group.)

If the battlegroup is set to retreat at half damage, damaged units automatically return to the repair facility, and upon being repaired, rejoin the battle group.

The power this gives you is sublime, you can actually effectively fight on 2 fronts while holding down base defenses or doing mop-up. In most RTSes as the battle progresses you'll start to wear your battlegroup out, production will languish, units will be left behind, and evenually you have to call off the attack, order/pickup new units, and re-organize for another push.

With Warzone 2100, you can order up replacements for your losses as they occur without leaving the front line, you group will self repair, and repaired units will automatically return to the battlegroup. That combined with target chaining, and other features allows you to leave a battle for a few seconds to focus on something else (e.g. switch between multiple fronts or handle some base construction) secure that your armie can take care of itself for a minute on its, and worst case will be forced to retreat.

The only real concerns is if you are completely outclassed and can't even survive retreating, or if your supply/resupply pathing gets intercepted (or the AI chooses to send your damaged units into the enemy to get to the nearest repair center).