The game takes place in two environments: the Metro itself and the surface. The Metro consists of inhabited stations and tunnels infested by mutants. Each station within the Metro is different, and the player will get to see and visit many of them throughout the game, hostile and otherwise. The surface is a very dangerous place, requiring the protagonist to wear a gas mask to survive, making it crucial to find corpses and containers and scavenge for gas mask filters. Should the mask start to crack and break the player has to find another one, otherwise Artyom will die.