*sighs* Yeah, Deadpool. Glad the character I loved since the early 90s is finally getting respect, but damn, he's going to be as overexposed as Wolverine at this pace.
Regardless, some quick ideas...
Doctor Strange- based around a 3rd person shooter engine, but instead of guns, various incantations and hexes.
SHIELD - C'mon dammit, super secret ops agency with flying cars and laser guns? How isn't this a game already?
Ghost Rider - Yeah, I know there was a game for him recently, but that doesn't count. Give me a sandbox game where I can drive around a city AND up the walls, massive demons to punish, as well as criminals that can be used as XP to build up the Spirit of Vengeance powers, etc. And you damn well better get Sam Elliott (possibly one of the only good parts from the GR movie) as the narrator.
Franklin Richards - ...or you can just pretend the kid from Limbo is him and just laugh and laugh and laugh...