Haunt is a horror RPG that is short enough that I would almost consider it a micro game. The system is a modified version of Onyx Path's system, where you basically add an attribute plus a skill and roll that many d10s hoping to get some that roll 8 or higher.
The uniqueness of the system, however, comes from the fact that players each have three dark secrets that the GM doesn't know about. Every time a player fails a roll, the GM gets to ask questions about these secrets. If the GM can guess all three of a player's secrets before the players can win the scenario, then that player is out of the game.
It's an interesting twist that makes this game a good choice for a quick and fun one shot if a group is looking for something a bit different.