An indie developer by the name 'Kazerad' was working on a two player game where each is trying to uncover the other's identity, and kill them. Sadly, he's abandoned the idea, but he posted everything you'd need to pick up where he left off.
I think "Murder simulator" was a good word for it. It was a game where you're trying to kill someone while acting like you're totally not trying to kill someone.
On his tumblr, Kazerad goes through a detailed explanation of the game, mostly talking about all the characters he designed for it. The storyline of the game sounds a lot like Clue (the movie):
Six astronauts are happily living alone in a small, off-world research facility when the power suddenly cuts out. Once the emergency lighting comes on, the astronauts discover their commander has been eviscerated.
Unbeknownst to the astronauts, one of their own is actually a shapeshifting monster known as a Harvester - a supernatural creature that feeds off the presence of death.
But unbeknownst to the Harvester, one of the unassuming astronauts is actually an agent of the Golden Claw - a secret organization tasked with taking down supernatural creatures. Hilarity ensues.
Just kidding! It's a bloodbath.
The thing that really makes this interesting are the game mechanics. They're an interesting twist on familiar ideas:
Ultimately, I opted for something turn-based and "Mafia"-like. One player, playing as the Golden Claw agent, wins the game by identifying and killing the Harvester. The other player, playing as the Harvester, wins by killing all the NPCs - at which point he/she will finally be strong enough to kill the Golden Claw agent. The roles are randomly assigned among the five characters each game, and both players have an incentive to keep their character secret - the moment one player identifies the other, the only way they can remain hidden is by literally, physically hiding.
So if any of that sounds good to you, and you're a game developer, or want to try your hand at being one, give it a shot. Read through the posts here, and download the art assets in the top post.