I've played Supers before in short games... one-shots or several-session runs. But I've never run or played in a long-term campaign about Supers, and I'm pretty sure its because the Supers genre is really focused on one primary thing-- combat.
We make all kinds of talk here about how D&D is a "monster-fighting game"... most of the stat on a character sheet is geared towards fighting monsters, most of a monster statblock is used in fighting against PCs... but the actual genre of "fantasy" is not one about fighting. Fighting happens of course... but fantasy was never designed with fighting being the end-all-be-all of what the genre is for. Whereas superhero comics have always have. The fight of the superhero versus the supervillain is always the climax. 9 out of 10 issues of any comic book will involve Supers combat. It's entirely a genre focused about this premise and promise... Supers characters using their super-powers to fight against other people with different super-powers. Yes, there will of course be other things that happen in any Supers book-- romance, communication, mystery, espionage, science, etc... but Supers books aren't about those things, those things merely are the ways that build towards that final fight.
Which of course is also why I think people sometimes see D&D as a game to be superhero-like... because D&D's "monster-fighting game" premise matches the Supers genre in that the climax of any session or any campaign ends up being a big fight against the bad guy.
And I believe this is why I've never really trucked much with the Supers genre in TTRPGs... because I just don't have the interest in combat when it comes to roleplaying games, I'm in it for the interactive story. How and where things progress. It's why every CRPG I play is always set at the easiest level... because once I reach a point in the story that turns into a fight... it's the fight's and story's resolution and where things go after that which interest me-- not spending countless times playing and replaying a fight over and over and over trying to "win" it at more and more difficult levels. To me that's entirely missing the point of an RPG. In an RPG of any type or genre, combat should be no more difficult or take any more time or be no more important than anything else one can do in the game. A fight and negotiation and an exploration of a location should all be of equal time, energy and import. And if it's not? And one thing holds way too much import (like combat is to the Supers genre)... I just don't have a desire or need to play it for extended lengths of time.
