Superman presents quite a few problems in his game design.
- You have to make him feel strong. To do this it is hard to create enemies for him. Likely you resort to aliens, monsters or machines because you can't just make grunts like in Batman because they would ruin the immersion if they didn't go down in a single hit.
- He is nigh invulnerable. If you dont have this feeling of being sturdy and taking a lot of damage and shrugging it off in Manly ways then you don't feel like Superman. This presents a problem with how you go about creating threats that feel believable to his character and yet are challenging without being game breaking. To hurt him you generally have to resort to Kryptonite or magic and having everything contain one or the other is a bit forced...it would take a really really really good plot device to stitch this up adequately without coming across as contrived.
- He flies. This is likely the biggest problem strangely. A melee character with laser eyes who flies has yet to really have a combat style that works. First off if the levels are too small you dont feel any real sense of wonder from his flight as you should. You'd need to be Just Cause 2 size or bigger. Second of all when you have a 3D action title and your main character can just fly the hell away how do you control story progression or ever really threaten them when they can just leave or skip to other areas? It often gets settled Spiderman style with objective points everywhere. It also presents problems in combat when he is best know for three things which are namely laser eyes, bashing things and flying tackles that dash in and out of crowds of enemies. Do you put enemies in the air to add excitement to flight? Do you give him an aiming system like Dark Void or Bionic Commando for laser eyes during flight or to target for tackles? Its difficult
- Laser Eyes...how do you get players to not use them constantly and turn this into a shooter? Superman was all about the smashing and strength, but giving such a character a projectile in a game makes it difficult to design enemies.
He's tricky to say the least. Personally, I'd setup the intro with a kryptonite bullet shooting him and severely injuring him so that I can make it so he could only glide for short distances like in Prototype. It'd also give me more leeway in setting up enemies that could really wear him down. I could add huge startup and cooldown to his heat vision due to him being injured as well. Also that move cannot function like a gun IMO. It needs to progressively do damage to enemies like slowly heating up a teakettle takes time. This would prevent abuseable zoning but allow for stuff like in Bionic Commando where you use the environment by say cutting down a billboard and then catching it to throw.
His enemy would have to encompass a whole city and be something believable enough to present out in the open brawl opportunities to you constantly. For this you have to turn the city into a warzone. This means likely Brainiac with an army of machines, or some viallin releasing all the Powered villains from prison into the city as a distraction to allow them to setup for something major (which doesn't exactly provide more than one guy at a time to fight unless they get backup troops somehow that are tough.), or Aliens/monsters.
Superman could use his super senses as an excuse for Radar and for how he gets his missions and his telescopic/xray eyes and senses can be used Prototype style for stealth and to gather intel to help him piece together how to find and stop what is going on.
The story needed to pull off all these elements would be very delicate. Its a house of cards and one push too hard could make Superman come across as weak, out of character, or boring. Its tough. The gameplay needs to have lots of over the top scale to its action. Lots of worms eye view camera pans to giant enemies or far off targets you can jump to in a single bound or target and bullet fly at/throw attacks at.
Lots of picking up the environment and cutting apart terrain is needed too.
Its got a ton of gameplay, but flight will either need to invent some kind of smooth sky target lock system so that it doesnt' turn into a camera clusterfuck or it will need nerfed into a glide or dash mechanic to contain it. Plus you HAVE to somehow deal with his nigh invulnerable nature and his strength being so ridiculously powerful in enemy design. So much to do...so much to have to reinvent, and sooooooo difficult to write reasons for everything.
Its possible, but it'd have to be a companies biggest project. It'd take years and a lot of money which is something most people never throw at this license.