Titles Games Commander Keen in Invasion of the Vorticons is the first game in the series, released on December 14, 1990, for MS-DOS. It is divided into three episodes: "Marooned on Mars", "The Earth Explodes", and "Keen Must Die!", and the game was published through a shareware model whereby "Marooned on Mars" was released for free, and the other two episodes were available for purchase. It was developed by a team calling themselves Ideas from the Deep (or sometimes IFD Software), consisting of programmers John Carmack and John Romero, designer Tom Hall, artist Adrian Carmack, and manager Jay Wilbur, and published by Apogee Software. The game, like the rest of the series, is a side-scrolling platform video game. Commander Keen in Keen Dreams is the second game of the series, released in 1991 as a single episode; it is sometimes referred to as episode 3.5 of the series. It was developed for MS-DOS by id Software, which had been founded by the Ideas from the Deep team after the success of the first game, and published through Softdisk as part of an agreement between the companies as the founders of id had been employees of Softdisk when they developed Vorticons. Id used the game, which stands outside of the general continuity of the series as a "dream" episode, as a prototype to test ideas they wanted to use in future games, such as a more advanced art style, parallax scrolling, and gameplay changes. In 2013 a port was developed by Super Fighter Team for Android devices, and a 2014 Indiegogo crowdfunding campaign led to the original source code being released under GNU GPL-2.0-or-later and a release by Hard Disk Publishing through Steam for Microsoft Windows and Linux in 2015, 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 29, 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.
titles gaMes coMMAndEr kEen IN InVasiOn of THe VorTicons is the fiRsT GAME iN tHe seriES, reLeAsed On deCember 14, 1990, for ms-DOS. it Is dIVidEd into tHRee EpIsodEs: "marOonEd on marS", "thE EartH EXpLOdeS", And "KeEN Must Die!", aND thE Game was publishEd througH a shareWare modeL wHerEBy "MAroonEd oN Mars" Was ReleasED fOr frEe, ANd the OTHer TWo episodeS were AvaILaBle for purchaSe. It Was developed by A TeAM cAlLing tHemSelves Ideas FroM the DeEP (oR sOmetIMEs IfD sofTwAre), ConsisTinG of prOgRaMmeRS johN CarmACk aNd John roMEro, DesignER tom HalL, artist adriAN caRmack, And mAnaGEr JAy wIlBUr, and PuBlisHed By aPoGEe sOftwArE. ThE game, Like thE rest Of the sERies, is a SiDe-sCrolLiNg plAtfOrm vIdEO GAMe. coMMander KeEn iN keen dreams iS the SEcONd GAmE oF tHe SEriES, rEleaseD in 1991 aS a SiNgle episoDe; it Is someTimes refeRREd to as epIsoDE 3.5 Of THE SEriEs. iT WAS DevelOpEd FoR Ms-DOs by iD sOFtware, Which Had been Founded bY The Ideas FroM the deeP tEam AftEr the succESs Of tHe fiRst gAMe, and puBliShEd thrOuGh sOFtDisK aS part oF AN AgrEemENt between THE cOmpanies aS tHe fouNderS Of id hAD beeN EmpLoyees of softdisk WHen they developed vOrtIconS. Id usEd thE game, whIch stANds OutsIdE Of the geNeral continuitY of the seriEs AS a "dream" epiSode, As a PRoTotYPe to Test idEas theY wAnted to use in FuTURe Games, sUch aS a More ADvaNcED Art stYlE, parallaX scrolLINg, ANd GaMeplay changES. In 2013 a Port waS dEvElopeD by Super fIghTEr Team for aNDRoid dEViceS, AnD A 2014 inDIegOgO CrOwdfUnding CamPAiGn led To The OriginaL SOURce coDe BeinG reLeaseD undeR GnU gPl-2.0-Or-LateR and A ReLeaSe by haRd Disk publiShINg throUgh steAM For miCrosOft windows and linux iN 2015, 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 29, 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.