In shortest possible terms – Kerbal Space Program is rocket science made simple. It’s a game of strategy, planning and execution – careful planning and proper execution give some of the most rewarding feelings achievable in video games.
The game revolves around Kerbals, little green humanoid aliens, who build space ships to get into orbit, or to land on other planets. It focuses on real physics, meaning constructing a proper space ship and sending it to outer space is an extremely challenging and fun task.
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, which is based on Earth. Despite being shown as funny cartoon-like little green men, sometimes lacking common sense, they have shown themselves to be able to construct very well-made spacecraft parts and perform experiments.