RimWorld is one of my favorite video-games of all time. From harvesting organs, to blowing up tribal settlements with anti-matter weapons, to making vast farms of rice and potatoes to feed my colonists. Until a few months into actually playing GURPS, I had never thought of a conversion until I had joined my first ever Play by Post GURPS campaign.
I had "played" as the Butcher of Merlach, Lucius Felix. I am not going to get into the details, but the game was shot down shortly after the start. I then decided, though I had barely any GMing experience with GURPS, that I would reform the campaign. I got together two players, created a scenario, and put together my world.
While those who have played the game might be thinking to themselves "How do you put a colony simulation game into GURPS?", well, I didn't. I am going to gloss over my first attempt, going immediately into my second attempt into this setting. The hunt for the pirate's treasure.
Taking inspiration from Borderlands, I had set up a simple yet exciting premise. The group were coming from cryptosleep onto a planet where a lost vault was hidden. Little did they know, that their ship's captain, Jimmy Treeward, who was not just a rebel separatist, but had a bounty on his head as well!
Before they discovered this, the group had made their way onto a space lounge, called the "Sky's End". The group had been walking around the mall-like structure for some time, when they noticed that someone in very expensive armor was tailing them through it. They purchased weapons at a pawn shop inside the mall, before getting shot at by the bounty hunter!
The fight was intense, with the group's crazy transhumanist Dalton blasting a bounty hunter's head off on a very hard roll! They narrowly made it out, not without sustaining serious injury, but were not out of the woods yet. Bounty Hunter ships were high-tailing them, firing at them. Only with a bold move to use his (illegal) psychic powers to repair the ship last minute, they would have crash landed!
The story continues for a long bit thereafter, but I am going to cut it there. You'll probably already see the enticing stories that can be born from this setting, because of the nature of it. Any tech-level from zero to twelve being on the table, psychic powers, cybernetics, dark and evil forces, bounty hunting, space travel, and other insane features make it feel vast and complex.
Now, the setting has it's issues, like any other. There is no FTL travel in the RimWorld universe, so people must use slow space colonization to bring the core of the universe to the stars. Along with this, information and technology spreads very slowly, with entire planets and civilizations being able to fall before the colony next to them knowing. My work around for this is called Ship Skipping, using the setting's psychic powers. The TL;DR is that using psychic powers, you can move your entire spacecraft far distances, making travel much faster.
This has given rise to many things, like the reformation of the Sophian Empire, spread of technology, and faster colonization. This will come back to bite me if I continue to play in this universe, as all of my games are connected, but I think the concept works well for GURPS RimWorld. Overall, it makes for an interesting setting, although you should play by the lore for the best experience.