One Leaves

One Leaves is a single-player horror video game for the Xbox and PC platforms. Based on a true story, it begins in a decaying urban environment from which you must escape. You face a number of challenges as you work your way through the game. As the story progresses, it becomes more obvious that speed is of the essence. Take too long with the various puzzles, and you'll end up stuck in the lounge. Figure out how to beat the NPCs against whom you're playing, and you'll reach the exit.

As the narrator explains at the outset, "Four enter but only one leaves."