Director Felipe Falanghe was hired by Squad in April 2010. At the time, the company did not develop software.[16] According to Falanghe, the name "Kerbal" came from the names he gave small tin figurines he installed in modified fireworks as a teenager. In October 2010, development on Kerbal Space Program was authorized by co-founder Adrian Goya but deferred until Falanghe had completed his projects.[16] Kerbal Space Program was first compiled on 17 January 2011. The game's first public release, version 0.7.3, was on 24 June 2011. The game entered beta on 14 December 2014, with version 0.90, and was released out of beta on 27 April 2015.
Version 0.7.3 was the first public release of Kerbal Space Program, and was released on 24 June 2011. It was downloaded over 5,000 times. Compared to future versions of this game, 0.7.3 was quite rudimentary. There was no stability assist mode, Kerbin did not rotate and the Sun was simply a directional light source. There were no fuel flow mechanics, no control surfaces, and no other celestial bodies. Later versions added additional planets and moons, as well as the ability to load and save collections of parts, known as "subassemblies". Tutorials were also added at this stage.[19] Version 0.24, titled First Contract and released on 17 July 2014, added the contracts and reputation system to the game's career mode; however, players were still able to play career mode without these features in the new science mode. Contracts reward the player with currency and reputation. Funds can be used to purchase rocket parts, and reputation results in better and more lucrative contracts.[20][21] The final alpha release, 0.25, included a new economic system, and a major rework of aircraft components.[22]
Version 0.90, nicknamed Beta Than Ever, was released on 15 December 2014.[23] This was the only beta update for Kerbal Space Program. Featuring extensively rewritten code for the editor, it introduced the ability to sort parts by several characteristics and to assign parts to custom categories. Players could now offset parts, including into space. Career mode featured building upgrades; only the creation of small rockets with low mass and a part count is initially supported, but the player can upgrade each of the facilities to increase size limitations or unlock other capabilities.
Version 1.0 was the first full release of Kerbal Space Program. It was nicknamed We Have Liftoff! and released on 27 April 2015. Version 1.0 completely overhauled the flight and drag model for a more realistic simulation, now ignoring drag on rocket parts which were occluded from the air flow. It also allowed for body lift, so that parts that were not specifically designed as wings (such as structural panels) could still generate lift. 1.0 added shock heating and heat shields, making atmospheric entry much more dangerous, as well as air brakes and procedurally generated fairings. All parts received internal modeling. Resource mining was added to refine into fuel or monopropellant. 1.0 also brought several improvements to Kerbals, who could now have various specializations. For example, "Engineer" Kerbals can repair wheels and landing legs. Female Kerbals were also added to the game.[24] Version 1.1, nicknamed Turbo Charged, was released on 19 April 2016, almost one year after the last major update. The game engine was upgraded from Unity 4 to Unity 5, resulting in a massive increase in performance, as well as a stable 64-bit client, removing memory constraints caused by too many mods being installed. Much of the game was rewritten to accomplish this.[25] Squad released Version 1.2, nicknamed Loud And Clear, to upgrade the game from Unity 5 to 5.4 and introduce performance and minor gameplay improvements. The patch entered experimental testing on 6 September 2016 and was officially released on 11 October 2016. Its main new features include communication satellites, relay systems, and KerbNet.[26] Several updates have been released since.
On 27 January 2014, it was revealed that Squad was working on an education-themed version of the game entitled KerbalEdu in collaboration with TeacherGaming LLC, creators of MinecraftEdu. It has since been released and includes an improved user interface for easier data gathering and summary, pre-made lessons that focus on certain constructions, options to use the metric system, and a "robust pedagogy" that includes information outside of the game that ties into its content.[27] Squad has also made an Asteroid Mission Pack, with full support from NASA. Released on 1 April 2014, it is based on the real-life initiative to send humans out to study asteroids.[11][28] The majority of the game's music was provided by royalty-free composer Kevin MacLeod, with the rest of the soundtrack having been written by Squad's in-house composer Victor Machado. The game's main theme was composed by lead designer Felipe Falanghe and arranged by Machado. On 5 June 2015, it was announced that Kerbal Space Program was being ported to the PlayStation 4 by Flying Tiger Entertainment. In August 2015, it was announced that Xbox One and Wii U ports were also in development by Flying Tiger Entertainment.[29] The game has since been released on the PlayStation 4 and Xbox One, but Squad has been quiet regarding the announced Wii U port. In January 2017, one of Squad's developers had finally broke the silence on the official forums, and admitted that despite initial enthusiasm to release the game on the Wii U, they claimed that various "external factors" has forced them to reevaluate supporting the console. They added that additional details will be announced at a later date.[30] On 17 March 2017, Squad announced a full expansion for the game; called Making History, it would be paid and contain new features. These new features included Mission Builder, which would allow players to create and edit their missions that players could complete by launching and operating various rockets and ships in the game, and History Pack, which would provide designed missions simulating important historical space endeavors that have been completed in real life. Squad announced on 7 February 2018 that the expansion would be released on 13 March 2018.[31] The expansion contains many parts inspired by those used in various rockets such as the Soyuz spacecraft and the Saturn V.[citation needed] Squad announced in May 2017 that Kerbal Space Program has been acquired by publisher Take-Two Interactive; this acquisition does not affect Squad's development or plans for the game and early backers will still get free DLC, and with Take-Two's help as a publisher, better support Kerbal Space Program on consoles to keep those versions to-date alongside the personal computer ones.[32] Kerbal Space Program will be one of the first titles published under Take-Two Interactives's 2017-launched Private Division, a publishing label aimed to support mid-sized development studios.[33] In late May 2019, Squad released the Breaking Ground expansion, which includes servos, pistons, new and redesigned space suits, and experiments which can be deployed to earn science over time.[34]