The game centres around the manipulation of "rules"—represented by tiles with words written on them—in order to allow the titular character Baba (or some other object) to reach a specified goal.
The player, usually, controls a character known as Baba, but it may be different in some levels. Each level contains various movable word tiles, corresponding to specific types of objects and obstacles on the field (such as Baba itself, the goal flag, walls and environmental hazards, and other creatures), linking operators such as "is" and "and", and verb tiles reflecting the properties of these objects (such as "you", which makes the object become controlled by the player, "push" to make them movable, "stop" to make them impassable, "win" to specify the goal, "sink" to make items drown in it, and so on). The object of each level is for the player to reach the goal by manipulating these tiles to create or modify "rules" by which they behave. For example, the goal can be changed by moving "is" and "win" blocks to another object, and the player can travel through objects by removing the "stop" trait from them. Levels can force specific rules by placing their blocks in a corner, so they cannot be moved. The game contains over 200 levels.