Time-Tested Gaming
1up has an interesting piece looking at games that have withstood the test of time, aging gracefully where others have not. Titles discussed include the Korean powerhouse Starcraft, Nethack, and the Sim series. From the article: "It's hard to label which games are suitable for repeated lovin' and which are forgettable. One gamer's Halo is another gamer's Superman 64. But when it comes to firing up a favorite, some adventures hold the same appeal they did when they were released years ago -- and jumping in for the fortieth round is every bit as pleasurable as the first time."
has been released for practically every game medium
The first game I thought of was Zelda, but it was nowhere to be found in this article.
I have followed Zelda games ever since I was a child, and even today, tons of people follow it. It was simply a perfect game. There's a community online that makes their own quests with an engine:
http://www.zeldaclassic.com/
Also, a person has redone the original NES rom and made another game that's fantastic on its own:
http://rha.cymoro.com/zelda3c/ZeldaC/
If you give it a go for the first time, prepare yourself to be disappointed. Be prepared to spend the first ~hour or so dying many times, mostly from starvation and YASD (Yet another stupid death). But if you get that through hour or so and last beyond around level 10, you will be hooked for life (not necessarily a good thing!). I would recommend reading some of the many guides on the net, but avoid the spoilers at least for the first while, it will spoil the satisfaction of discovering things yourself (like #dipping your sword into a poition of poison will make your sword poisoned as a small example).
Ultima Online is still played *a lot*. There are hundreds of free shards around the globe and the official paid servers are still also online (I doubt they're still profitable, though).
Then, there's also Quake (yes, the first one). It's still played around the world. Quake mods such as Team Fortress (which paved the way to full modification mods as we see today) and some simpler mods such as Total Destruction are still played and there many active communities for these games.
Although America's reality is a bit different, these facts are completely true in another countries such as here in Brazil, for example, and maybe in many other developing countries. This is the positive side of not being able to have the latest graphics card or whatever: people don't focus that much on graphics. They worry about fun. That's why UO is specially popular: people can make their own world and play with their friends, with a server hosted on their own machine. Almost any PC can run Ultima Online without problems (I used to play it on a K6-350 with 32MB RAM).
The culture is really different. The most commercially succesful game here in Brazil currently is Ragnarök, a crappy online RPG. It has terrible mixed 2d/3d graphics and people are still paying to play it. Because everyone can play it. It's not like Half-Life 2 where maybe 10% of the computers can even run it at a barely playable level.