RimWorld 1.7 moves the colony simulator from Unity to Ludeon’s in-house Waylith Engine, with the first build available on Steam’s unstable branch. The headline is a large technical change, but the player-facing takeaway is deliberately familiar: Ludeon says the game should look and play the same while improving performance across several demanding parts of a long-running colony.
What is changing in RimWorld 1.7?
Ludeon says Waylith replaces Unity as the engine behind RimWorld 1.7. The studio’s own tests show a broad 2–4x performance improvement compared with Update 1.6, including faster startup, loading with large mod lists, map and world generation, and general simulation ticks. That is a useful target for players who already know how quickly a heavily modded colony can become CPU-bound.
The most specific example is a late-game colony that Ludeon measured at 2.2x the performance of its 1.6 counterpart. The studio also says a 1,500-mod pack loaded in six minutes instead of 14. Those are Ludeon’s stress-test results, not a guarantee for every PC, save, or mod list. The same caveat applies to any performance headline: the size of the colony, active mods, hardware, and background load will shape the result. GoldCrit’s PC performance coverage is a useful reminder that a large technical gain still needs context.
Do existing saves and mods work?
According to Ludeon’s Official Waylith announcement, 1.6 saves load on 1.7, and saves made in 1.7 can be opened again on 1.6. That cross-compatibility makes the unstable branch easier to test without treating the beta as a permanent one-way migration.
The studio also says the vast majority of mods work without changes. Some may show a yellow “potentially unsupported” warning simply because their version number has not been marked for 1.7 yet. Mod authors can publish a 1.7-compatible version after testing, which should remove that warning for players. Ludeon says Waylith also exposes newer C# language features and makes complex mods and visual effects more practical without the same performance concerns.
How can PC players test the update?
RimWorld 1.7 is currently on Steam’s unstable beta branch. To try it, open RimWorld’s Properties in the Steam library, choose the Betas tab, and select the unstable branch. If Steam offers a separate launch choice, use “Play 1.7 Unstable.” Ludeon’s Steam announcement says the normal branch remains on 1.6 for now, so players who want a stable colony can stay on the main version.
There is one hardware warning worth taking seriously: Ludeon says PCs more than 10 years old may not run 1.7. That is a limitation to test before switching a primary machine, especially if an older system is running a large colony that currently performs acceptably on 1.6. Keep backups of important saves even though the studio describes the formats as cross-compatible, and treat the unstable branch as a testing environment rather than a finished replacement.
Should you try RimWorld 1.7 now?
If you have a late-game colony or a huge mod list, RimWorld 1.7 is worth testing on a copy of a valued save. Waylith gives the update a meaningful technical foundation without changing the game’s familiar presentation, while modders gain more room for complex systems and effects. Check the mods that matter most and compare the result on your own hardware.
If your current 1.6 colony is stable, there is no forced migration today. The main branch remains available, and the 1.7 unstable build is best understood as an unusually important public test of the engine that may power more of Ludeon’s future work.
