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Using Math To Tune a Video Game's Economy
An anonymous reader writes: When the shipping deadline was approaching for The Witcher 3, designer Matthew Steinke knew there was a big part of the game still missing: its economy. A game's economy is one of the things that can make or break immersion — you want collection and rewards to feel progressive and meaningful. Making items too expensive gives the game a grindy feel, while making them too cheap makes progression trivial. At the Game Developers Conference underway in Germany, Steinke explained his solution.
"Steinke created a formula that calculated attributes like how much damage, defense, or healing that each item provided, and he placed them into an overall combat rating could be used to rank other items in the system. ... Steinke set about blending the sub-categories into nine generalized categories, allowing him to determine the final weighting for damage and the range of prices for each item. To test if it all worked, he used polynomial least squares (a form of mathematical statistics) to chart each category's price progression. The resultant curve (pictured below) showed the rate at which spending was increasing as the quality of each item approached the category's ceiling value."
"Steinke created a formula that calculated attributes like how much damage, defense, or healing that each item provided, and he placed them into an overall combat rating could be used to rank other items in the system. ... Steinke set about blending the sub-categories into nine generalized categories, allowing him to determine the final weighting for damage and the range of prices for each item. To test if it all worked, he used polynomial least squares (a form of mathematical statistics) to chart each category's price progression. The resultant curve (pictured below) showed the rate at which spending was increasing as the quality of each item approached the category's ceiling value."
As you say, you want to feel like your economic choices have consequence, and not just for your pocketbook. If I buy all the fish in town, then not only should the price of fish go up, but the fishing industry should spend its money in predictable locations and boost other industries.
As my subject line alludes, the real place this crops up again and again is in space games. If I'm buying and selling the complete available product of a planet in some particular industry, that should have significant effects. Or, if I blow up a bunch of cargo ships carrying spaceship parts, then that should have significant and immediately noticeable effects. Instead, none of this is true at all in basically any game but EVE.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Yep, it annoys me a bit when at the beginning of a game, it costs a gold coin to stay a night at the inn at the beginning of the game, but it costs 100 gold coins at the end of the game in the "end game" areas. Granted, these are not games that are attempting any sort of "serious" world-building like Witcher 3. It still seems lazy, though - they should use other means for removing money from the player.
I've also thought it somewhat lazy for developers to have a single coin type (typically "gold coins"). I've always thought that designers who resorted to that sort of currency never really understood how incredibly valuable a single gold coin actually is. Common goods are typically highly over-valued, and weapons and armor actually tend to be undervalued. It's ridiculous for a fish to cost 5 gold coins while a sword, even a basic starter sword, might only cost 100. Granted, I think most gamers don't really care about such things, but just once I'd like to see a videogame at least attempt to make a realistic stab at this.
MMOs (particularly "theme park" types) have a particular problem with their economies, in that goods are essentially created from nothing in limitless supplies, and the final products from crafting last an infinitely long time. As such, they need to figure out how to create viable viable "gold sinks", or ways of removing money from the economy in ways that doesn't irritate the players too much. I've always thought that, no matter the solution they came up with, it always ended up feeling rather artificial (or simply inadequate), and it often ended in a massively inflationary economy.
I'm still working my way through the first two Witcher games. As soon as I'm ready to play the third, I'll have to take some note of the general economy and see if it ended up as satisfying to play as one hopes.
Irony: Agile development has too much intertia to be abandoned now.
Magic Online, the digital version of the famous trading card game, is currently undergoing a kind of "economic recession". Basically, trading for cards is facilitated by event tickets (roughly $1 in value) and booster packs (containing 15 cards, roughly $4 in nominal value) that act as a digital currency. Events are entered using event tickets as payment and they pay out as booster packs to the most winning players. This is done to avoid gambling laws.
What has happened is that number of players entering events has gone down while the amount of booster packs floating around has increased, so that the going price for booster packs has fallen to around 2 tickets (so $2 equivalent). This has made entering events unattractive for all but the top players, since the expected value of the prizes to win are now half of what they should be, while the entry fees remain the same. This further drove the number of players down, with many people selling their collections and leaving Magic Online.
Several months ago Wizards of the Coast set up an "economy strike force" that supposedly consisted of several people with "advanced math degrees" to solve this conundrum of a depressed economy. They finally announced their "solution" some weeks ago. It was to double the entry fees and basically cut the prizes to 75% of the old one.
The economy predictable tanked even harder, leading to more players selling out.