Brat is an isometric action puzzle in which the player guides Nathan, the brat of the title, through a series of twelve levels. The isometric landscape scrolls up-screen, imposing a time limit on each level. Whilst Nathan automatically walks forwards at the same rate, if he is diverted he will begin to lag behind. If the screen catches up with him, the player loses one of three lives and must restart the level. Nathan is not controlled directly: the player must place icons onto the level to guide his movement. There are a variety of items that can be collected by Nathan, then later placed by the player to bypass certain obstacles: deadly spring toys can be suppressed with a lead weight, and building blocks can bridge gaps, for example.