A childhood dream come alive created by Double Fine's lead animator, Tasha Harris, Costume Quest 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. Explore the various neighborhoods, complete quests, discover hidden areas and trick-or-treat your way through this spooky Halloween night.

The PC version of Costume Quest extends the adventure with the added-in DLC pack Grubbins on Ice. Players get to visit a whole new level set in the monster universe of Repugia. That means all new quests! New characters! New enemies! New costumes! New Battle Stamps! New Creepy Treats! And a snowman! Help the monsters overthrow Araxia to bring peace back to Repugia!