The game still needs some kinks worked out but it's $15 on Steam.
Basically there are 6 players. Two of those players are "infected". Everyone needs to work together to figure out who's infected, while the infected need to secretly kill the other players during the "lights out" phase. During lights on phases other players can vote out who they suspect are infected if they have majority vote.
The game has more to it, but it really is a lot of fun. I linked the Deceit Twitch live channels if you want to see game play.