So you’ve proven your worth as a trivia, music and shooting master. What’s left for a real nerd to do? Deal plain old playing cards to fight opposing forces, obviously. Clear off the coffee table for this fantasy oddity: Players deal specially coded cards onto a fabric mat where an included USB camera scans them. It sends the information to the screen where your forces are pitted against your opponent’s. Weird? Oh, yes. But it’s surprisingly fun, as long as you play against a real person.