Jettomero is a giant amnesiac robot that decides its purpose is to protect humanity. Taking control of Jettomero, the player explores the universe in search of marauding monsters to fight. One planet in each solar system is home to a giant monster that must be defeated in a QTE battle in order to reveal a wormhole that will transport the player to the next solar system. Much like those of Mirrormoon EP, the planets are unrealistically small and can be circumnavigated in just a few seconds.
On the surface of planets, Jettomero walks in a clumsy manner similar to Grow Home's BUD. The human inhabitants of each planet consider Jettomero to be a threat and will attack the player with a variety of weapons and traps that cause Jettomero to stumble and stagger, but do no permanent harm. The player can choose to avoid conflict and unnecessary destruction when exploring a planet, or to wreak havoc and destroy every feature on the surface; though there is no in-game acknowledgement of either play-style, trophies will be awarded for certain extreme actions.
The game is visually quite striking, with cel-shaded graphics a saturated colour palette.