My vast experience in games, Please read moderators

I suggest fighting between friends
or an arena where he would have a rating level of player something
battles in groups
gain armor missions "premium"
more deals
a chat where players could interact with each other
as for example DDtank
to transfer the stone, of the armor to armor in the main character and secondary
think of something that increases the competition between players
it is essential for a game
more heroes like superman, or magneto
a hero who makes the other strong
a hero or become another weak
strengths and weaknesses in a character
some better and more detailed list of friends
battle group
the course of the game post more ideas