Space Ace follows the adventures of the dashing hero Dexter, who prefers to be called "Ace." Ace is on a mission to stop the villainous Commander Borf, who is seeking to attack Earth with his "Infanto Ray" to render Earthlings helpless by reverting them into infants. At the start of the game, Ace is partially hit by the Infanto Ray, which reverts him into an adolescent, and Borf kidnaps his female side-kick Kimberly, who thus becomes the game's "Damsel in Distress." It is up to the player to guide Dexter, Ace's younger incarnation, through a series of obstacles in pursuit of Borf, in order to rescue Kimberly and prevent Borf using the Infanto Ray to conquer Earth. However, Dexter has a wristwatch-gadget which can optionally allow Dexter to "ENERGIZE" and temporarily reverse the effects of the Infanto-Ray to turn him back into his adult self "Ace" for a short time, and overcome more difficult obstacles in a heroic manner.
