Costume Quest
Costume Quest is a turn-based RPG by the famous Tim Schaffer. The plot is simple enough: You're two twins going out for trick or treating, a goblin kidnaps one of them, and the other has to save the day. Each costume you wear turns into an epic version in battle (e.g., a vampire costume will transform you into an actual vampire) with their own special abilities. Some even help you outside of battle, like the french fry one helps coax people with its tantalizing smell of fries (yeah, don't ask).
I had a lot of fun with this game, although I could tell it was aimed at a younger audience. The battles were pathetically easy, for one. My main gripe is the quests were repetitive. Each area followed the same formula: knock on doors for candy, find rare trading cards for NPCs, bob for apples, locate kids playing hide and seek.
It's a shame because I think the concept is great, but they didn't make it shine to its full potential. Nevertheless, I had a lot of fun. The writing is good, the art style is adorable, and the game's short so even the repetition doesn't stink too much. Whether it's worth the money XBox Live and PSN are asking is another issue.