Costume Quest

Costume Quest incorporates elements of exploration of adventure games and character growth of role-playing video games. In the exploration part of the game, the player character explores their surrounding area, starting with their neighborhood, then a mall, and then a country town. In these areas the player can complete quests through trick-or-treating that reward the character with hints to the sibling's location, more candy (a type of currency for interactions with other children), and costume parts that can be used to alter the character's costume. The character can also befriend up to 4 non-player characters that can help with some aspects of quest solving.

At times, the player characters will encounter monsters, leading to the battle mode for the game. Here the children become giant versions of what costumes they are wearing, along with abilities reflected by that costume; for example, a child wearing a makeshift robot costume becomes a giant mechanized robot, while a child wearing a medieval sweater becomes a knight in armor and sword. Battles are turn-based, allowing the player to select attacks, blocks, or a special move that requires hitting a quick time event at the right moment to achieve maximum damage to their foes. Winning battles leads to additional rewards towards the player's main quest.

The game takes place on Halloween. Fraternal twin siblings Reynold and Wren are new in their neighborhood and are asked by their mom to make new friends in the neighborhood. The player at this point chooses which sibling to play as, marking them as "in charge". The two dress in their costumes, with the non-playable character dressing as a piece of candy corn and the playable character dressing as a robot.

A monster sees the non-playable sibling, and kidnaps him or her. The player character must now save their sibling in time and be home before curfew. The player character trick-or-treats at houses, tracking the monsters and their sibling from the neighborhood, then to a mall, and then to a country town. Along the way, they meet fellow trick-or-treaters Everett and Lucy, who join their party.

Costume Quest is a result of a series of "Amnesia Fortnights" that Double Fine had used during the period of Brütal Legend's development when they were unsure of their publisher. During the Amnesia Fortnights, the team split into four smaller groups and worked on prototypes for potential future games, later presenting these to the rest of the Double Fine team for review. All four prototypes were well received internally, and the ideas were set aside once they began work on Brütal Legend again. Following completion of that game, Double Fine believed that Electronic Arts had authorized them to continue work on a Brütal Legend sequel, but discovered later that the sequel had been put on hold indefinitely, leaving the studio with no projects.

Instead, Tim Schafer turned back to the Amnesia Fortnight products and sought to develop those as smaller games among several publishers. Two of them, Costume Quest and Stacking, were picked by THQ for publication as downloadable titles.

Costume Quest received "generally favorable reviews" on all platforms except the Xbox 360 version, which received "average" reviews, according to the review aggregation website Metacritic. Reviewers frequently praised the game's art style, humor, and Halloween setting, while several considered it too short and its turn-based combat simple or repetitive. GameSpot described it as charming but found the combat basic, and Game Informer similarly felt the gameplay did not match the game's presentation.The game was given the "Best Downloadable Game" award at the 2010 Spike Video Game Awards.

The Xbox 360 version of the Grubbins on Ice DLC received "favorable" reviews according to Metacritic.