What is Costume Quest?
It's a sort of RPG game. The main thing is to find your kidnapped sister. Meanwhile you are to do "quests" for people, go trick-or-treating, trading cards, and finally leveling up your costumes. Yes, the costume you are wearing are actual fighting characters in a turn-by-turn based gameplay when you meet evil goblins (or whatnot). (Along with some other stuff, I just can't remember right now).
Looks childish, but it's really fun. I got it last October, and I liked it very much. (and I'm no kid... or teen!)