Yes, Doom was the beginning of the FPS genre as we know it. But Half-Life marked the beginning of an evolutionary leap for the genre. Quite simply put, Half-Life is, and will remain, one of the greatest games ever. I really can't put the gameplay experience into words, but I remember when I first played this game almost ten years ago, I was absolutely absorbed. Seriously. Absorbed. At the time, the mods were sharp, fun, and novel. Counter-strike. Firearms. Team Fortress Classic.