Marvel Super Hero Squad Online was a browser-based MMO in which players control characters from the Marvel Universe. Players can choose to play the game's brawler missions, (these missions are similar to the gameplay found in classic brawler arcade games like The Simpsons, Streets of Rage, etc.) a physics based sandbox in the HQ (a mode similar to the Sims) a card game reminiscent of Magic the Gathering, and an overworld / lobby where people can meet up with their friends. The game was both subscription based and free to play with the option of buying in-game objects. All of the most popular Marvel characters were available for play.