Hatris is a puzzle game where players must stack hats on mannequin heads that fall from a conveyor belt two at a time. The goal is to create stacks of five hats of the same kind, which then move down to be shipped out of the factory and reward the player with cash bonuses.
The gameplay involves using strategy to clear the hats as quickly as possible, while also dealing with increasing difficulty levels that introduce new hat types. Players can aim for a higher score by stacking hats together more efficiently.