The Citadel, the gravity gun, the headcrab. Valve Corporation’s 2004 first-person shooter was a masterclass of game design that has endured, inspiring waves of video games, film and TV since.
Half-Life 2's third DLC episode was never finished because Gabe Newell and company didn't just want to finish the Half-Life 2 story arc, but to do something big and innovative with the game design, ...