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 a single direction of climbing only. Hazards include falling, "smart darts" (small bullets that fly slowly across the screen, but when orthogonally lined up with Jumpman, greatly speed up and shoot straight in his direction) and other hazards that are unique to a certain level.
Points are awarded for each bomb defused, with bonus points available for completing a level quickly. Jumpman's game run-speed can be chosen by the player, with faster speeds being riskier but providing greater opportunity to earn bonus points.