Marvel have one of the most recognisable character rosters in any media franchise, featuring gods, mutants, vigilantes and friendly neighbourhood Spider-Men, and yet it's rare you'll ever find a game that reflects the publisher's full range of characters.
While in early console generations you may have seen more unique titles, it seems that these days we only seem to get crossover games or Spider-Man games. (I love Spider-Man, but we've had five console Spidey games in the last decade!)
The thing is, sometimes it's better to have a game that focuses on just one character rather than an ensemble, like we're seeing in the new Avengers game. Focusing on one superhero allows for the gameplay and story to be fine-tuned to fit that character in the best way possible, and with so many characters at their disposal, Marvel could dip into pretty much any genre of video game and make it work.
With the idea of a Marvel Gaming Universe gaining more and more traction over the past few years, it may not be too long until we start to see more heroes get their own games.