In Bad Rats, the player controls the rats that try to kill their prisoner, the cat, in a cruel and unusual manner.
The goal of the game is to kill the cat. Each level is a maze with rats on one side, and the imprisoned cat's cell on the other. An object like a bomb, a heavy safe or a chainsaw lies prepared next to the cat. The goal is to navigate anything across the maze to make the deadly object fall and kill the prisoner. The rats themselves can die a grisly death in the process, but as long as the cat is dead, the level is passed.
The game is centered around creating physics-based contraptions with the resources given to the player. The rats cannot kill the cat directly, and they have to make a kind of Goldberg machines and test them before using them on the cat. They can use rockets, trampolines, bombs, and other devices. The player places his or her rats across the level, taking into account their roles and abilities. For example, there's a rat that beats objects with a baseball bat, a rat that fires itself from a cannon, and a heavy fat rat, among others.
Bad Rats is infamous for its rude and overly simplistic visual style. It also became highly controversial and received a lot of criticism for its uncensored portrayal of bloody violence and gore. The game became a sort of a meme in the gaming community, and some claimed it was one of the worst games ever to be released on Steam.