In my GUT CHECK thread I said a lot of things, but the one I feel most strongly about is to keep the roster to X-TYPES ONLY
A more inclusive roster will just repeat what fails on these other games: too broad a scope.
If everyone is x-sphere and the game gives a reason for no more than 2 factions to exist, then they're all kept together, role playing together.
If you add in Avengers...more splintering
Add in space: more splintering
Add in Asgard: MORE splintering
Add in a magic faction: MOAAAR SPLINTERING
Next thing you know, you have a game with 32 characters role playing as part of 20 factions, and no one role plays with anyone outside of their preferred clique.
Dont be afraid to say: This is an X-Sphere game. You love the mutant civil rights drama, the characters, the setting, the history. Come here and play mutants
Then allow NPC cameos of the big bads and outside influences:
- The Avengers come to enforce registration. Time to fight the Avengers
- Sinister, Apocalypse, etc are all great for plots
- Doom visit Utopia
Long and short of the idea is to keep the PLAYERBASE focused on one aspect of the super hero world to keep them together and make their characters important. While you may have mutants that use magic (Magick, for example), doing this will keep Magick's character functionally important to the other PCs, rather than creating some Strange/Constantine/Zatanna hit squad that pulls the character further away from the core of rp for exclusive time.
No, instead make Magick important to the mutant community, one of their few magical experts, which will come in handy when Mephisto sucks them all into Limbo to fight demons. (Kyle/Yost/Young New X men run)