The object of the game is to defuse all bombs in a platform-filled screen. Jumpman defuses a bomb by touching it. According to the story, these are placed on Jupiter by terrorists. Jumpman can climb up and down ladders, and of course jump, and there are two kinds of rope each allowing one direction of climbing. Hazards include falling, 'smart darts' (small bullets that fly slowly from sides of the screen, but when orthogonally lined up with Jumpman speed up and shoot straight in his direction) and other hazards that are unique to a certain level.