Kerbal Space Program is experimenting with a partnership program through which gamers who refer others to the engineering-and-spaceflight simulator receive some cash for the evangelism.
The program is focused to externally hosted content — that is, YouTube, livestreaming services and mods or other constructions - and requires that someone referred to Kerbal's store buys a copy.
It's a test program, KSP's creators emphasize. "We are going to see how this works and decide after a period of time if it is something we will continue. We reserve the right to cap the number of participants, to change the program, including ending it."
Those interested need to register here.