The player controls a nascent space program operated by Kerbals, a race of small green humanoids, who have constructed a fully furnished and functional spaceport (known as the Kerbal Space Center, or KSC) on their homeworld Kerbin, similar to Earth.
Kerbals are generally shown as funny cartoon-like little green men, sometimes lacking common sense, resulting in an endless stream of flight volunteers with no care for safety procedures, but they have shown to be able to construct very-well-made spacecraft parts and perform experiments in the lab.
Gameplay consists of constructing rockets and spaceplanes out of a provided set of components and launching them from the in-game space center's launch pad or runway, then going on to complete their desired mission while averting catastrophic failure.
The game has been praised for its realistic representation of orbital mechanics. Every object in the game except the celestial bodies themselves are under the control of a Newtonian dynamics simulation. Rocket thrust and aerodynamic forces are applied accurately to a vehicle's frame based on the positions in which the force-generating elements are mounted. The strength of the joints connecting parts together is finite and vehicles can be torn apart by excessive or inappropriately directed forces.
To get started with the Kerbal Space Program. Visit the official page here.
*This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article for Kerbal Space Program.