Costume Quest is a rollicking Adventure/Role-Playing game that unfolds on Halloween night across seemingly peaceful suburban neighborhoods, a mysterious village carnival, and a monster-infested shopping mall. Created by Double Fine's lead animator, Tasha Harris, the game follows the adventure of a group of young friends who must rid their neighborhood of monsters using only their wits, their bravery, and their home-made costumes. Players go door-to-door collecting candy, points, cards, battle stamps and quest assignments as they prepare themselves for Combat Mode — where they transform into larger-than-life versions of their costumes. Each costume that comes to life provides its own unique set of superpowers that players will need to battle Halloween's worst monsters.

It's Halloween Night in Auburn Pines and bickering twins Wren & Reynold are the new kids in town, ready for some fun, scares and candy! In the beginning cutscene, you must choose between one of the twins. The one you DO pick gets to wear the robot costume, while the one you DON'T pick ends up in a silly but rather convincing candy corn costume. When your brother/sister is kidnapped by monsters who have mistaken him/her for a giant, talking candy corn, it's up to you and the magic of Halloween to go on a rescue mission and save him/her from the monsters and their wicked Commander - Dorsilla the Witch.