Superman

Sunsoft and the Superman license has a complicated history. An NES game was in the works, but was changed to "Sunman", for unknown reasons when development was close to completion. That game never made it out. There is a Genesis version of this game, which came out in 1992. By comparison of the graphics, I would not be surprised if Sunsoft intended to simply port the Genesis version to the SNES, although the screenshot in the preview below doesn't appear to correspond to any place in the Genesis version. The SNES was finally graced with a Superman title with the release of The Death and Return of Superman. Perhaps the SNES game was cancelled because it would have come too close to the release of that game. Another possibility is that the SNES version of Superman eventually became The Death and Return of Superman, but that would be pure speculation (it came out in mid-1994).

A simple demo of Superman was discovered in 2019. It is completely unplayable, and shows Superman flying through an alien landscape. I do not think this kind of scenery exists in the Genesis version. The Superman sprite graphics are similar, but not the same, as the Genesis version. Considering how early this is (possibly over a year before it was cancelled), it is hard to make conclusions of what this game would have looked like in the end.