Kerbal Space Program

In Kerbal Space Program, the space programme begins in an assembly building. You connect tanks, engines, cabins and other parts, then test whether the design can complete the planned flight. Mass, thrust, fuel supply and staging order work together. Adding another tank helps only if the resulting craft can lift its weight.

After launch, the game requires an understanding of orbital motion. Gaining altitude is not enough: speed and direction matter. A map shows the trajectory, and manoeuvre nodes let you estimate changes to the route in advance. Rendezvous, docking and landing become problems you can break into individual actions and test with another launch.

Cartoon Kerbals soften the encounter with complex physics while preserving visible consequences for mistakes. Sandbox mode offers parts for free experimentation, while Science and Career modes add research and constraints. The connection to actual spaceflight also appeared outside the game: NASA invited the community to recreate the OSIRIS-REx mission. The full 2015 release grew out of public development that began in 2011.