Bouba/Kiki is a cooperative communication game based on the psychological Bouba/Kiki Effect, which is the finding that people tend to make the same associations between sounds and shapes, irrespective of their language or culture. For example, people will tend to associate the nonsense word bouba with a rounded shape and kiki with a spiky shape.

The cards in Bouba/Kiki display a nonsense word on one side, and a simple illustration on the other. In the basic game, you are faced with a set of three of these words and one shape, and must decide which word goes best with the shape. Points are earned by choosing the same target as your teammates.

The game contains six scenarios that expand on this idea, each containing five missions that gradually increase in difficulty and complexity. Each scenario presents a different communication-based setting, such as spacefarers making contact with an alien race, spirit mediums looking into the beyond, or toddlers playing together at a nursery.