the game engine for Brütal Legend was "essential" for Costume Quest, allowing the team to quickly reuse the existing technology without the licensing costs for other third-party engines. Schafer estimated the total budget for the game at about $2 million. A software bug that interfered with game saving was discovered after release, and while Double Fine was able to isolate and correct it, the cost of certifying the patch, estimated to be about $40,000, prevented them from releasing it at first. They did release it later as a Title Update. Release The game is a downloadable title and was released on October 20, 2010 on the PlayStation Network and Xbox Live Arcade services. A port to Microsoft Windows through the Steam platform was released about a year later. It was later released on Mac OS X and Linux as part of the Double Fine Humble Bundle. The original Costume Quest prototype was released for Microsoft Windows as part of the Amnesia Fortnight 2012 bundle on November 19, 2012. Expansions An additional downloadable chapter, "Grubbins on Ice", was made available on December 21, 2010, alongside a free patch to correct some of the game's performance and gameplay problems. Taking place some time after the events of the main game while winter falls upon the kids, they find a portal to the monster's world, Repugia, where Lucy is captured by the monsters during a revolution. The other three kids don their costumes to help save Lucy. While many of the core game's features carry over into the add-on, new costumes and abilities are available in the expansion. Windows version Costume Quest was originally released as an Xbox 360 and PlayStation 3 downloadable game. According to Schafer, while they would have liked to create a version for Microsoft Windows, they as the developer did not have the final say on which platforms would be supported. Schafer commented that THQ did not see a financial benefit for creating the Windows version at the time. However, a year after Costume Quests initial release, a version of the game for Windows was released through the Steam platform. This version was funded by Steven Dengler's Dracogen Strategic Investments, who had also previously funded a Mac OS X port of Double Fine's Psychonauts a few weeks before this new release. The Windows release includes the "Grubbins on Ice" content. Dengler had contacted Schafer and Double Fine in 2011