RimWorld Ditches Unity for Its Own Waylith Engine, Promises Up to 4x Performance

RimWorld is getting a new heart. Ludeon Studios announced on October 12 that update 1.7 will move its long-running colony simulator off Unity and onto the Waylith Engine, an in-house engine built by the studio itself. The headline claim is performance improved by two to four times, with the game looking and playing exactly as it does today.

The announcement, posted on the game's Steam news page, reads less like a feature list and more like a declaration of independence from one of the industry's most widely used engines. RimWorld has run on Unity since its release more than a decade ago. Version 1.7, available now on Steam's unstable beta branch, replaces that foundation entirely. Ludeon says faster startup, faster load times with large mod lists, faster map and world generation, and better ticks per second are all part of the package.

The claim that will matter most to players is the one about late-game colonies. RimWorld's simulation-heavy design means sprawling bases with dozens of colonists, hundreds of animals, and hundred-plus mod lists have historically ground even powerful PCs to a crawl. Ludeon's own stress test of a late-game colony ran 2.2 times faster on 1.7 than on 1.6. That is the studio's own measurement, not an independent benchmark, but for anyone who has watched a huge base crawl at triple speed, the number alone will get attention.

The numbers Ludeon is betting on

The most dramatic figure in the announcement is the modpack stunt. Ludeon loaded a pack of 1,500 mods and watched the load time fall from 14 minutes to 6 minutes. Fourteen minutes is not a loading screen; that is a lunch break. The studio was careful to note that these are its own results and that individual gains will vary with your PC and your mod list, which is the right caveat and one worth taking seriously until more players have run their own colonies on the new build.

The specific example Ludeon cites, a colony of 40 colonists, 200 ducks, and more than 100 mods, is telling. It describes exactly the kind of mid-to-late-game save where Unity's performance has visibly degraded over the years. Ticks per second, the figure that measures how quickly the simulation advances, is the metric that matters here. Large settlements slow down as the game processes colonists, animals, and jobs, even when graphics rendering stays smooth. An improvement in ticks per second is not the same thing as higher frame rates, and it is worth keeping that distinction in mind when reading the 4x ceiling.

Ludeon loaded 1,500 mods and watched the load time fall from 14 minutes to 6. For a game whose players treat thousand-mod lists as normal, that is a headline in itself.

Why the mod ecosystem matters most

Engine swaps usually mean breakage. When a live game with a decade of saves and mods changes its foundation, the expected outcome is a wave of broken mods and incompatible saves. Ludeon says none of that is necessary. Save games work in both directions between 1.6 and 1.7, and the studio expects the vast majority of mods to work without changes from their authors. Some mods may display a yellow "potentially unsupported" label, but that can simply mean the version number changed, not that the mod is broken.

That compatibility promise is the boldest part of the announcement. RimWorld's modding scene is one of the most active on Steam, and a compatibility break would have been a community disaster. Instead, Ludeon says the new engine supports newer C# features and makes it easier for modders to create complex modifications and custom visual effects. If that holds up in practice, the engine swap is not just a performance story; it is a bet that the modding ecosystem will get more capable, not less.

There is one real caveat. Ludeon warns that PCs more than ten years old may not run 1.7, and it is asking players with very old hardware to report issues on the official RimWorld development Discord. For a game that has historically run on modest machines, that is a meaningful shift in system expectations, even if the studio says it may be able to make changes to help.

The Unity exit, in context

RimWorld is not the first game to leave Unity behind, but the way it left is unusual. Most studios that abandon Unity do so between projects, when no players are affected. Ludeon is swapping the engine under a live game with millions of owners while promising that nothing visibly changes. That only works because the studio kept the game's look and behavior identical, a constraint that made the engineering far harder but the player experience far safer.

The timing is also hard to ignore. Unity's relationship with developers has been strained since the runtime fee controversy of 2023, and several studios have since re-evaluated how much of their future they want tied to a single engine vendor. Building a proprietary engine is the most extreme form of that re-evaluation. For a small studio like Ludeon, it is a bet that owning the stack is worth more than the convenience of Unity's tooling and talent pool.

That bet has a technical logic beyond independence. RimWorld's performance problems were never really about graphics; they were about simulation. A general-purpose engine like Unity carries overhead for every system it supports, and a colony sim with thousands of entities per map does not benefit from most of it. An engine built around RimWorld's specific simulation needs can cut straight through that overhead, which is plausibly where the 2-4x gains come from.

What comes next

The update is in unstable beta now, with the stable branch staying on 1.6 while players test. The real verdict will come from the community's own benchmarks: colonies of different sizes, mod lists from dozens to thousands, hardware from a decade of builds. Ludeon's numbers are a starting point, not a verdict.

Buried at the end of the announcement is the line that matters for the future. Ludeon teased that "RimWorld isn't the only game on Waylith. We're working on something new!" An in-house engine built for simulation-heavy games only makes financial sense if it outlives a single title. The studio is signaling that Waylith is not a one-off migration tool but the foundation of whatever comes next. Watch what that next game turns out to be; it will tell you whether Waylith was worth the decade-long detour.