I've said it before and I'll say it again, supers can fight anywhere!
Especially with games like SuperSystem, narrative will really drive the experience, so having a reason to fight on the terrain you already have is all you need for a fun game.
Yes, you can blow hundreds on a giant city set-up like me:
Or you can play on whatever's handy:
Just flip through some comics and see where the fights are happening, just taking a quick look at the pile on my desk, there are industrial plants, shipyards, tropical islands, Dark Age castles, outer space, alien worlds, deserts, cities, abandoned mines and way more besides.