Erm Doom is a first person shooter. It's a bit different than a choice based adult game. Since the main purpose of games like Doom is to stay alive, by slaughtering everything in your path, you don't need multiple routes because the game element is provided by all the adversaries you come up against. In a choice based adult game, the game element is provided by having enough choice to decide your own destiny, rather than have it mostly made up for you by the Dev, because there's only one route that you can't deviate from. That's not really what a game is. You can call anything a game, but that doesn't mean that is a game.