It could have all gone so wrong. We know you hear that a lot in game retrospectives, but this is serious. Yes, BioShock could have been about zombies in a Nazi bunker, Borderlands could have looked like gruel, and Tabula Rasa might have featured butterfly-winged men fighting each other with books. But Half-Life is more than just a game. It triggered a movement: a massive change not just in the way first-person shooters were made, but video games as a whole. It set new standards for player immersion, narrative quality, and combat AI, and opened the doors to modding in...