Mad Rat is a 1-player arcade game for the Apple II.

Three blind field mice named Masecy, Karson, and Marshall have been trapped in the Zacks 6th Avenue department store. Numerous dangers lurk there, and the Mad Merchandiser of Zacks takes perverse pleasure from throwing cheese at them for food, but then making it downright dangerous for them to get it.

The player controls a single mouse on a series of platforms moving in alternating directions. The player can move left or right, and can also jump to higher platforms, or fall down below. Numerous pieces of cheese recurrently appear on the screen, and every time the player collects 10 pieces, the conveyor belts move faster. A cat on the bottom of the screen will pace back and forth, and randomly jump to different platforms, and if it catches the mouse, it's a lost life It's also a lost life from falling through the hole in the bottom of the screen. If the player collects the green power-up at the top of the screen, they become a Mad Rat, whom can destroy the cat if they come in contact.

The player has a total of 3 mice, and when all are lost, it's game over.