Ludeon Studios announced on October 12, 2026, that RimWorld is leaving Unity for Waylith, an engine the studio built itself, starting with Update 1.7. The update is live now on Steam’s unstable beta branch for Windows, macOS and Linux. It is not the main release yet, and most players will stay on 1.6 until it is. The game still costs $34.99.
RimWorld has a long patch record behind it. Ludeon ran it as a public alpha from November 2013 and shipped 1.0 on October 17, 2018. Five expansions have followed: Royalty, Ideology, Biotech, Anomaly and Odyssey, the last in July 2025. Putting a new engine under a game that old, with that much DLC and a Workshop full of mods, is a job most studios save for a sequel. Ludeon is shipping it as a version number.
For anyone who has not played it, you run a small colony of crash survivors. You assign jobs, build rooms, grow food and keep people sane. Over all of it sits a storyteller, which is the AI director that picks the next raid, plague or cold snap. Big late-game colonies, with dozens of colonists, animals and stockpiles, are the heaviest load the game carries, and a long mod list adds to it.
What Ludeon says Waylith changes
The numbers come from Ludeon’s own testing. The studio reports overall performance two to four times better, with faster startup, quicker world and map generation, and more ticks per second. “We stress-tested a late game colony and saw 2.2x better performance on 1.7 compared to 1.6,” Ludeon wrote in the Steam announcement. A pack of 1,500 mods that took about 14 minutes to load now takes about 6. Results will vary by PC and mod list, the post adds.
The game on top of the engine does not change. “The game looks and plays exactly the same,” according to Ludeon. Saves move both ways: a 1.6 colony loads in 1.7, and a 1.7 save still loads if you switch back. So trying the beta does not put an existing colony at risk.
The yellow warning modders will see in 1.7
Most mods should run unchanged. Some will show in yellow as “potentially unsupported,” which Ludeon says only reflects the new version number. Mod authors clear the warning by publishing a version marked for 1.7. PCs more than 10 years old may not run 1.7 at all, and Ludeon asks those players to report it on the official Discord.
To try it, open RimWorld’s properties in Steam, pick the “unstable” branch under Betas, and choose “Play 1.7 Unstable” if Steam asks. Ludeon gives no date for 1.7 on the main branch, and the post does not say why the studio left Unity.
Ludeon also says a new game is in development on Waylith, with no details yet. GamingOnLinux called it a tease, which is fair; the announcement says little more than that it exists.
If your late game crawls, the unstable branch is worth a try, since your saves can go back with you. Everyone else can wait for 1.7 to reach the main branch.
