Betrayal at House on the Hill

You explore a haunted house, placing room tiles as you go, until the "haunt" triggers and one player becomes the traitor with a secret objective to kill everyone else. There are 50 different haunts (100 with the expansion), so you never know what the game will become — sometimes it's werewolves, sometimes it's aliens, sometimes your character gets possessed by the house itself. The randomness makes it chaotic and occasionally unbalanced, which is exactly the point. It's less a strategy game and more a horror movie you play. 3-6 players, 60 minutes.