Quake II

While the original was a fine game, it had a little problem of only looking nice on those expensive 3Dfx video cards. Quake II, meanwhile, was much more forgiving, and many of us took it into our hardcore hearts and fragged each other into delightful oblivion until the wee hours of the morning. It offered a streamlined and fluid brutality that's still satisfyingly memorable all these years later. It was also quite friendly to amateur creators, granting the community a treasure chest of maps, character models, character skins, game modes, and more.