A first-person horror/suspense sort of thing. The game takes place in a series of interconnected rooms, each with 3-4 doors and with multiple ways to get from one location in the map to another. In order to complete the game you need to complete a number of objectives to unlock the exit (such as finding fuel for a generator that opens the last door), which will have you zig-zagging around the level trying to find and use various objects that are lying around. The only other thing in the level is a single NPC monster that randomly wanders the various rooms. When the monster is nearby the lights in the room will begin to flicker, when it is in an adjacent room and/or is about to enter your room the lights will go out completely. The monster then projects a sort of searchlight that it uses to look around the room - if you get caught in this searchlight you die instantly, but if you manage to hide from the monster it will just move on into another room. It can also hear objects if they are knocked about and can hear the player if you move without crouching or walking slowly, at which point it will actively start hunting the player in and around the area it heard the noise (if it finds nothing after a certain time, it will return to its neutral state and continue wandering). This could allow the player to throw items across the room to distract the monster, giving them enough time (hopefully) to escape. Since the player will be hiding whenever the monster is nearby they likely won't get a clear look at it, which may add to the atmosphere of the game.

Something like this may have been done before, but if it has I hadn't heard of it. This is mostly the culmination of a few days of random daydreaming, and I'm not sure if I'd be able to make something like this or even if it would be any good as a game. Still, comments are welcome.