EIM Group intended to release a Superman game for the Nintendo Entertainment System, only to drop the license partway through development, which founder Kenji Eno claimed was the result of DC Comics not wanting the title character to be seen dying or taking damage. However, given that these restrictions were not present in earlier Superman video games or in The Death of Superman (an arc in the comic books published concurrently with the EIM game's intended release date), other theories suggest that the game was created as a pitch for DC, which was withdrawn before submission due to the NES approaching the end of its lifespan.

Regardless, EIM decided to retool the game as an original IP called Sunman, named after the intended publisher, Sunsoft. All visual and textual references to Superman were excised to fit the change, though everything else was left unaltered. Despite the retool, the game received no known publicity and was ultimately shelved; it would eventually leak online in 2003, while the Superman version (consisting solely of the first level) surfaced six years later. Despite its cancellation, elements from Sunman would later be recycled in Thinking Rabbit's Superman, which was published by Sunsoft in the United States.