The four color world of Superhero comics is provided for on my Genre Tree, and I would simply loot my Champions source books, and adventure books to create the initial sandbox. I describe my initial ideas for the campaign setting here.
You do not have to restrain your branch to the Champions Universe by Hero Games. The Comic Book world has thousands of pages, and almost any subject matter is touched upon. What they all have beating within its Krypton-vulnerable heart are characters thrust into struggles with shifting moral clarity. Anxiety wrought tension wraps every action with the cost of failure high. This is usually juxtaposed with the player's incredible powers and abilities.
Comic Books came into their own as a legitimate literary genre with their incorporation of modern psychological thought. Sarte, Jung, Einstein, all their philosophical constructs come bursting forth in spectacular eruptions of power in comic books.
This branch can be as long or short as you care to make it. Here is mine;
2.2 Space Opera, Comic Books
2.2.1 Champions Universe