Game: Costume Quest

Costume Questis a fairly traditional action RPG freshened up almost entirely by its concept. InCostume Quest, you play one of two twins who go out trick-or-treating one Halloween night. Once out, they encounter a race of candy-stealing goblins commanded by an evil witch, one of whom mistakes one of the twins' for a giant piece of candy thanks to a candy corn costume. The other twin (the one you control) vows to rescue the missing sibling by amassing a vast collection of Halloween costumes and teaming up with other kids.