Betrayal at House on the Hill is a cooperative horror exploration game where players explore a spooky, tile-laying mansion only to have one of them secretly turn into a traitor. In the first phase, players work together to explore the randomly generated house by revealing new room tiles, triggering events, and collecting items. Once enough ominous omens or specific conditions are met, the Haunt begins, revealing a specific scenario (one of 50 different possibilities) that identifies a traitor among the group. The remaining survivors must then work together to complete a new set of objectives to defeat the traitor, who now has their own unique powers and victory conditions. This shift from cooperation to a two-sided, competitive battle, combined with the randomized house layout and Haunt scenarios, ensures a tense, highly thematic, and deeply replayable horror experience.