Daredevil Season One. Yes, I know, Season Two, and Jessica Jones, and as of this weekend Luke Cage, but it came out on shiny discs today so I can watch it on my TV rather than my computer, so it’s time to talk about it again. So there.
A human or very-slightly-superhuman vigilante hero operating at night is a sensible place for a sub-universe to start (see also Arrow) because everybody knows the archetype (hint: Ben Affleck also played Daredevil and now...) and fighting crime is a sound basis for TV.
We get stunts (including one stunt sequence everybody talked about) more than effects. Human gang bosses, anonymous thugs with guns and the occasional ninja are enough of a threat so we don’t have to worry about adapting villains. Avoiding publicity means the world can look a lot like ours even though it has heroes and gods fighting aliens somewhere else.
There are entire RPGs for street-level supers, as well as sourcebooks for wider-ranging supers RPGs. Focusing on the crime, it would be possible to do with something like Gumshoe, or Angel for the action.