I'm working on ideas for a video-game. I want to give the player a lot of customization options. The power type I have in mind is the ability to manipulate and generate energy. Be that Magnetic, Ionic, Electric, Photonic, or Gravitational energy. If you want to play as an electrically-charged Brute, you can do that. A speedster, you can do that. If you want to play as a Gravity-Manipulating gunslinger, you can do that. What I wanted to do was give the player an infinite amount of potential to play with, but the amount of experience you can amass is limited, thereby limiting how powerful of a character you could make. What I am wondering is, if I began writing a story focused on such a character, would that character be to powerful to sustain the interest of an audience?
If you need a yard stick, the Superman Returns video game was a perfect example of having too powerful a character to keep engaged with.
I think your idea of infinite potential/limited capacity is an ideal way to balance it out...provided each of the powers/abilities at it's maximum is equally advantageous, otherwise, certain powers may be exploitable.
As a suggestion I'd say use a similar method of power progression that was found in inFamous 2, where your abilities levelled up as you explored them (like getting 5 headshots got you your sniper skill).
With the versatility of the powers, you'll have to design challenges that can be solved equally by each power, and maybe some that can only really be taken down by certain methods, encouraging re playability.
Stories about powerful characters, such as Superman, usually have to tie into their humanity. As Superman says, he has to keep himself in check, or things could go horribly wrong. It'd be easy to go full tilt, but the folks he cares about might be harmed because of it. If you character is truly on the road to greatness, maybes set up some moral choices. While we would probably think we'd be stoic boy scouts with great power, really think about how a mere mortal would act now that a very large part of his life has become easier. If the situation is outside of the norm, what happens when your fundamental understanding on how life works is shattered in mere seconds.
You could probably write a piece that children would be more likely to be heroes than adults would, because many children are naive to the evils the world has to offer. Unless they become severely jaded early on, a child still believes in entities such as Santa, the Tooth Fairy etc. so the sudden acquisition of superpowers wouldn't be all that shocking, in fact, it'd be quite cool.
Adults, being aware of how the world works, and that corrupt people can get away with quite a lot, might go Vigilante, or maybe Anti-Villain. If the experience was jarring enough, maybe they use their powers to focus on the things that have personally wronged them, or they could go flat out insane.
Really, my advice is design a basic human character, then truly think how they would act if, one day, they were given superpowers. What would influence their decisions from that point on?