Portal 2

Players take the role of Chell in the single-player campaign, as one of two robots—Atlas and P-Body—in the cooperative campaign, or as a simplistic humanoid icon in community-developed puzzles. These four characters can explore and interact with the environment. Characters can withstand limited damage but will die after sustained injury. There is no penalty for falling onto a solid surface, but falling into bottomless pits or toxic pools kills the player character immediately. When Chell dies in the single-player game, the game restarts from a recent checkpoint; in the cooperative game, the robot respawns shortly afterwards without restarting the puzzle. The goal of both campaigns is to explore the Aperture Science Laboratory—a complicated, malleable mechanized maze.