On October 12, 2026, Ludeon Studios announced Update 1.7 for the colony management simulation game RimWorld, which switches the game's engine from Unity to the studio's own "Waylith Engine." The update can already be tried in the Steam beta. According to the studio, the game looks and plays the same as before while delivering a 2x to 4x performance improvement over previous versions. For players with long-running colonies or large numbers of mods, sluggish performance is a major limit on how far a colony can grow. So how much difference will this engine overhaul make? Let's look at the specific performance gains and compatibility with existing data.
New Engine Delivers 2x to 4x Performance Gains: How Real Are They?
According to Ludeon Studios' official announcement, a stress test using a late-game colony recorded 2.2 times the processing performance of version 1.6. Game startup time and load times in heavily modded setups have been shortened, and performance has improved across a wide range of areas, including map and world generation and in-game simulation updates.
However, the published "2x to 4x" figure does not necessarily translate directly into higher rendering frame rates. Frame rate (FPS), which measures how many times per second the screen is drawn, is a different metric from TPS (Ticks Per Second), which measures how many times per second the game's internal processing runs. In RimWorld, even if the display is smooth, the game slows down if the colony simulation can't keep up. That makes it important to distinguish which processes have actually been sped up.
Specific load-time measurements have also been published. In an environment with 1,500 mods installed, load time dropped from 14 minutes to 6 minutes. That is a reduction of about 57%, meaning the game loads in less than half the previous time.
Note that this roughly 57% figure is calculated from the version 1.6 and 1.7 load times published on October 12, 2026. It does not mean that in-play processing performance has improved by 57%.
These results also come from Ludeon Studios' internal testing. Detailed specifications of the PC used and the list of mods have not been released, and the studio says the degree of improvement will vary depending on the environment.
To check the real-world effect, it would be effective to use the same save data and mod setup and compare load times and in-game processing speed separately.
Custom Optimizations Built Up Since the Unity Days
Even when it used Unity, RimWorld relied on custom systems developed for the game's own specific processing.
In its official FAQ, Ludeon Studios explains that it built its own systems to manage in-game objects and the passage of time. The studio's view is that a game like RimWorld, which manages thousands of objects on a tile-based 2D map, has different processing needs from the continuous 3D spaces Unity excels at handling.
This shows that a 2D game is not necessarily light on processing. Even when the visuals are simple, the game must constantly update the state of a huge number of characters, animals, and facilities behind the scenes. Even with a general-purpose engine, there is considerable room to optimize such game-specific processing independently.
That said, this FAQ does not explain the internal structure of the Waylith Engine. While it confirms that the studio already had its own processing systems, it is unclear how much easier that made the move to the new engine.
This is also not the first performance improvement for RimWorld.
In Update 1.6, announced in June 2025, Ludeon Studios also carried out large-scale optimization. It made character pathfinding multithreaded, changing it to run multiple tasks together, and also multithreaded lighting, improving areas that tend to become heavily loaded in the late game.
In addition, measurements on a development PC showed that game startup time fell from 18.57 seconds in version 1.5 to 4.66 seconds in 1.6. Moreover, the 1.6 measurement was taken with one more expansion installed.
However, this startup-time comparison and the load time in the 1,500-mod environment announced this time differ in both what was measured and the conditions. It is therefore not possible to simply multiply the two improvement rates to calculate an overall speedup from earlier versions.
Given this history, the move to the Waylith Engine can be seen as a major turning point: a development team that had accumulated RimWorld-specific optimizations has finally taken the step of overhauling the game engine itself.
Which internal changes led to this performance gain will have to wait for more detailed technical explanations. Meanwhile, another important question for players is whether they need to rebuild the colonies and mod setups they have built up in order to benefit.
Save Data and Mod Compatibility Also Maintained
Another notable point about this transition is compatibility with existing setups.
According to Ludeon Studios, save data from version 1.6 can be loaded in 1.7 as is. Data saved in 1.7 can also be taken back and used in 1.6.
In other words, returning to the previous version after trying the new engine is an anticipated use case. Not having to restart colonies that took a long time to develop is a major advantage for existing players.
The studio also says that most mods will work without any changes by their authors.
However, because the version number has changed, some mods may display a yellow warning saying they "may not be supported." This does not necessarily indicate a functional problem; it may simply be because the supported-version information has not been updated.
Ludeon Studios is calling on mod authors to confirm that their mods work properly in 1.7 and then publish them with the supported version stated explicitly.
That said, save-data compatibility and mods working correctly are separate issues. Even if a save loads, there is no guarantee that every installed mod will run without problems.
The studio also says that version 1.7 may not run on old PCs more than 10 years past their manufacture date. A PC that could play earlier versions will not necessarily run the new engine.
On the other hand, the move to the Waylith Engine also brings new benefits for mod developers.
Ludeon Studios explains that the new engine makes the latest C# language features available and makes it easier to develop complex mods without hurting game performance. It also says that large-scale graphics changes and custom visual effects will be easier to implement.
If it becomes easier to add new expression and features while maintaining compatibility with existing mods, this could have a positive effect on future mod development. How far these possibilities actually extend, however, will become clear as developers make use of the new engine.
Waylith Engine to Be Used in New Game; Update 1.7 in Beta Testing
The Waylith Engine will not be used only for RimWorld.
In this announcement, Ludeon Studios also revealed that it is developing another new game using the engine. At this point, however, the title, game content, and release date have not been announced.
The studio has thus indicated a policy of using its own engine across multiple titles, but it is unclear whether this new game is a sequel to RimWorld or an entirely different work.
Update 1.7 is currently available as a Steam beta.
To try it, right-click RimWorld in your Steam library, open "Properties," and select the "unstable" branch from the "Betas" tab. If the update does not start automatically, restart Steam, and if a choice appears at launch, select "Play 1.7 Unstable."
The regular release branch remains at version 1.6, so this is not yet a stage where all players are automatically moved to the new engine.
What to check in the beta is how much of a performance gain you get in the colonies you normally play, and whether your familiar mods work correctly.
This engine overhaul may make it more comfortable to run large colonies that were previously difficult because of heavy processing. The benefits may be especially noticeable in setups with many colonists and animals and more than 100 mods installed.
If significant performance gains can be achieved while preserving years of accumulated save data and mod setups, it would be a major step forward for existing players as well. Attention will now turn to how much improvement is seen across different PC environments and mod configurations.