Players control their spacecraft in three dimensions with little assistance other than a Stability Assist System (SAS) to keep their rocket oriented. Once built, the craft can be launched by players from the KSC launch pad or runway in an attempt to complete player-set or game-directed missions while avoiding partial or catastrophic failure (such as lack of fuel or structural failure). From this space center players can create rockets, aircraft, spaceplanes, rovers, and other craft from a provided set of components. The player administers a space program operated by Kerbals, a species of small green humanoids, who have constructed a spaceport called the Kerbal Space Center (KSC) on their home planet, Kerbin. In-game Kerbals, Valentina Kerman on the viewer's left, Jebediah Kerman on the right, standing on the launchpad

A sequel, Kerbal Space Program 2, has been announced for a 2023 release. Two expansions for the game have been released as downloadable content: Making History in March 2018 and Breaking Ground in May 2019. An Enhanced Edition was released for Xbox One and PlayStation 4 in January 2018, and for PlayStation 5 and Xbox Series X/S in September 2021 by Private Division, a publishing subsidiary of Take-Two Interactive. In May 2017, Squad announced that the game was purchased by video game company Take-Two Interactive, who will help support Squad in keeping the console versions up-to-date alongside the personal computer versions. People such as Scott Manley and organizations involved in space travel have taken an interest in the game, including NASA, the European Space Agency, United Launch Alliance CEO Tory Bruno, CEO and CTO of SpaceX Elon Musk and Peter Beck, CEO and CTO of Rocket Lab. Popular mods have received support and inclusion in the game by Squad. Kerbal Space Program has support for user-created mods that add new features.

The game was released out of beta on 27 April 2015.

The first public version was released digitally on Squad's Kerbal Space Program storefront on 24 June 2011, and joined Steam's early access program on 20 March 2013. The game features a realistic orbital physics engine, allowing for various real-life orbital maneuvers such as Hohmann transfer orbits and orbital rendezvous. In the game, players direct a nascent space program, staffed and crewed by green humanoid aliens known as 'Kerbals'. Kerbal Space Program ( KSP) is a space flight simulation video game developed by Mexican developer Squad for Microsoft Windows, macOS, Linux, PlayStation 4, and Xbox One.

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