I was listening to the Ken and Robin Talk About Stuff podcast and they once again mentioned the idea that you ought to be able to name a core activity of your game. It doesn't mean that the activity is the only thing you'll be doing, but it's the main thing.
So my first attempt at defining the core activity for my favourite niche-of-a-niche activity (superhero RPGs) is "Defeat the bad guys and preserve order."
I was also listening to the Fat Man on Batman podcast, where Andrew Kreisberg mentioned that in the Flash TV show writers' room they have a sign that indicates the recipe for each show (Heart, Humor, Spectacle, in that order of importance). Kind of the same thing...it's their statement of core activities.
You notice that bad guys aren't mentioned? In fact, I'd say that the villains are often the weakest part of the Berlanti DCTV-verse. The season bad guys are generally good, but the individual episode bad guys can be quite weak. Supergirl in particular has this problem right now.
If you have players who are committed to the story and the relationships (the kind of players who would take on the game Masks, for instance), that might be totally okay. If your players came up through Champions, though, and they expect bad guys, that would be a problem. "We are good guys and we always win because the opposition is pretty wimpy."
The Base Raiders game makes this explicit....I just wish I liked the system more, because there are details that I like a great deal. In that game, the players defining goals means that they also define the core activity.
So here are some other statements of core activities for superhero games and how they might affect the campaign.
We salvage stuff either before others or in dangerous places. This is less combat and more situational puzzles, with the possibility of rivals and possibly some legal loopholes.
We rescue people, from natural and unnatural disasters. I was trying to think of something that was super and would use super abilities, and be heroes, but not have your traditional punchy-fighty structure. The characters are first responders, essentially, to great disasters.
We are the superhero support team, who make them look good, despite resistance from them and the other side I had thought of this one some time ago as a campaign that had every player representing both a member of the support team and the superhero. The two might be attached to each other or not. It was either going to be structured as a prep-fight thing, or as a series of flashbacks during the fight: every time a hero wanted to use a retcon or said that something was available, I was going to flashback to how it got there. (The latter might be interesting in a story, but I couldn't see a way to make it work as a roleplaying session.) I loved the "Our people meet their people to discuss where the fight will be" scene, though: "It turns out your original nominee is owned by a mob boss we're beholden to. That's off the table. We'd like this place, because it's due to be destroyed, and we'll split the demolition fee with you." This also implies a lot more social stuff and relationship stuff than the others.