Superman 64 still blows my mind, because they nailed the Timmverse vibe with the N64's typical untextured polygons - while the character was so damn popular that the box art has no text. And then it's a series of unforgiving time-trials. Just a heaping plate of green-fogged frustration. It came out in 1999! It wasn't some launch title. Blast Corps had nonviolent property destruction two years earlier. The system was lousy with collectathons. Replacing bad guys with robots was infamously A Thing for at least the Turok games.

The game should have been a GTA prototype where you're only capable of doing good things, contextually. A power fantasy where of course flying toward a crowd swoops over them, and of course you can only throw cars at locked-on evil robots, and of course there's no possible way your character, who literally Superman, needs a god-damn HP bar.

How is the first character to properly explore the mechanics of an invincible protagonist... Wario?

The clever workaround for players being trying to be dicks is to say Bizarro's on Earth, and obviously thinks he's Superman. So any time you go completely over the line or fuck around beyond excuse, you get a soft game-over where you catch your reflection and it's not Kal-El.

What I'd pitch is a fairly short game with replay value in optimization. It's a day in the life. Superman has the ability to solve every problem in the city, that day. Superman has the ability to solve several major natural disasters happening around the globe... and still solve every problem in the city, that day. You, the player, are going to jump through your ass trying to schedule or predict more than about half. It has to be fair. There has to be a way, on every single playthrough, without memorization or guesswork. But it can be obscenely hard. It can be controller-through-television levels of difficult, both intellectually and mechanically, because that's in-theme. It underlines how good the man himself must be, in order to stop every mugging in Metropolis, instead of just the ones he comes across. And it lets you feel his frustration when even one slips through the cracks.

Anyway, escalate through a few specific "heavy" days, spread across a month or so. At first you're handling petty crime across town, with an invitation to rescue people from rooftops when a dam bursts in another state. By the end you're fighting Brainiac atop the Daily Planet, and while he limps away from having all three of his dicks twisted, you find a quiet moment to help a child climb out of a tree. High-level play involves hearing about a disaster before it happens, so you can stop the dam bursting in the first place. Or throw a tornado back into the clouds, or redirect the faultline from an earthquake, or whatever the problem is on this playthrough. It's variable enough that you can't just fly somewhere pre-emptively (most times) but frank enough that you might prevent it the first time.

Knowing what's right to do isn't easy, but it's simple. Knowing how to do all of it at once is neither.