Quake II

no matter how old this game gets its still one of the if not the best 3d shooter out to date. The online following is huge, and you don't get sick of this game...ever. I've been playing it ever since it came out and i only have a p150, game looks like ass on my computer compared to everone elses, but the game is so fun it doesn't even matter. And when you have a good computer it kicks even more ass because all the textures look so good under colored lights.