Stimpy’s Invention has the player take control of either Ren or Stimpy through six side-scrolling platform stages. The main gimmick used throughout gameplay is either character being able to use each other as a form of attack, such as Ren pulling off Stimpy’s nose as a projectile thrown in an upward arc. The player can switch between Ren and Stimpy on the fly, allowing access to the other character’s unique attacks. The game supports multiplayer, with no split-screen.