Sunman was a game developed for the NES by Sunsoft, and was originally intended to be a Superman game. Similar to Journey To Silius, however, they lost the rights to the property during development. Sunsoft attempted to remove the trademarked elements and make a game out of it, and nearly did, but ultimately decided not to release it. In fact, this game has the distinction of being one of the few NES titles to never see any kind of pre-release advertising. Its existence was finally discovered years after the NES bit the dust by retro enthusiasts.
I tracked down a copy of the game and gave it a try here in this video: