Raven Software and Marvel had a good working relationship during development, which ensured that almost any character they wanted playable, as an NPC or cameo, made it into the game. In regards to how the roster was selected, Marvel pushed for the big name characters or characters they were planning to turn into major franchises in the future (i.e. Spider-Man, Wolverine, Iron Man), while also advocating for lesser-known heroes (Moon Knight and Luke Cage). Raven Software strongly advocated for Deadpool and the Hulk. To gather information on the heroes, Raven primarily used Wikipedia and comic books sent over by Marvel to research what characters to add to the game, and character picks were frequently shuffled around during development, even a few months before release.