and OS X in 2016. A Nintendo Switch version was released by Lone Wolf Technology in 2019. Commander Keen in Goodbye, Galaxy was released for MS-DOS on December 15, 1991 as the second main game in the series. Consisting of episodes four and five of the series, "Secret of the Oracle" and "The Armageddon Machine", and stylized as Commander Keen in Goodbye, Galaxy!, it was developed by id and published through Apogee. Like the first trilogy of episodes, "Secret of the Oracle" was released for free, and the other episode sold by Apogee. The game incorporates a more polished version of the graphical updates in Keen Dreams, along with further gameplay changes and additions. Commander Keen in Aliens Ate My Babysitter is the final id-developed game, released in December 1991 for MS-DOS. Originally planned to be the third episode of Goodbye, Galaxy and sixth episode overall, it was changed before development began to be a stand-alone game—stylized as Commander Keen in Aliens Ate My Babysitter!—published as a retail title through FormGen. Due to differing timelines between FormGen and Apogee, despite being numbered as the sixth episode it was developed in between the fourth and fifth; it also features a modified engine from Goodbye, Galaxy. Commander Keen was released on May 30, 2001 for the Game Boy Color. Developed by David A. Palmer Productions and published by Activision, it was created as both a sequel and homage to the series as a whole, and does not have an episode number. Id was not a major partner in development, though it retained editorial control over the game, and Adrian Carmack contributed some artwork. The idea for a Game Boy Color Keen game came from John Carmack and id, who approached Activision, which in turn proposed Palmer as the developer. Cancelled and compilation releases After the release of Goodbye, Galaxy and Aliens Ate My Babysitter in 1991, id Software planned to make a third set of episodes for the following December, titled Commander Keen in The Universe is Toast!. Beyond the proposed title and release date, shown in the epilogue of the two games, no design work was completed before the game was cancelled due to the success of id's Wolfenstein 3D (1992) and development focus on 3D first-person shooters such as Doom (1993). John Carmack noted in 1999, when referencing the project that became the Game Boy Color game, that the original