C.O.
Are you looking for food ideas AND theme ideas??
Food?
Do some type of tostada shell or flat tortilla like "Captain America's" shield.
Sugar Cookies and decorate like Captain America's shield.
If the kids have expanded palates?? Green Goblin Guacamole.
Use cookie cutters or shape individual pizzas to the shape of the "SUPERMAN" logo.
Games:
Bean bag toss - use open and emptied soda cans or bottles with the villain pictures pasted/glued on and let the kids knock the villains down.
You can create an obstacle course using hula hoops for the kids to jump into or crawl through or even use 2 liter bottles filled with sand or rice to have the kids side-step through without knocking over.
For the girls? Wonder Woman lasso's - use licorice - red - since there is no gold.