This game is tough. It doesn't seem as polished as their (Sunsoft) Batman games.
Superman seems so delicate in this game. It's so unSuperman-like. No one seems to get a real Superman game that's really memorable.
There's this comic called Mann and Superman by Michael T. Gilbert. In this story, a down-and-out unemployed crook manages to magically switch bodies with Superman. Basically, Clark is relegated to taking all the consequences of the crook's mismanaged life and the crook takes all the glory of Superman's fame and powers. After some time, Clark in the crook's body, makes improvements, he gets a job and become a good father to the crook's son while the crook finds that everyone wants a piece of him. Even after doing a good deed, he messes it up by causing massive property damage and everyone hating him.
In the end, he finds being Superman is harder than he expected.
I think a good Superman game should be like that. He should be invulnerable but the game's difficulty would be focused on trying to be a moral paragon and doing things that would embody him as a symbol of hope and goodness.
"*Sob* Everybody expects Superman to be perfect 24 hours a day. Nobody's that good. Decisions! Decisions! All the time! I hate it" - from Mann and Superman.
Something like that.