RimWorld Drops Unity for Its Own Waylith Engine in Update 1.7, With 2 to 4 Times the Performance
By CriticalPixel ·
RimWorld is dropping Unity. Ludeon Studios announced on Monday that update 1.7 moves its colony sim onto the Waylith Engine, an in-house engine built by the studio itself, and the headline claim is a 2 to 4 times performance gain. Your saves carry over, most of your mods carry over, and the studio says the game looks and plays the same as before. That is a big promise for a colony sim that has spent years buckling under its own mod lists, and the early community numbers suggest Ludeon is not bluffing.
What Ludeon actually announced
The announcement went up on the game's Steam news page and spells out the plan in plain terms. Update 1.7 swaps Unity for Waylith, the studio's own engine, and Ludeon says its tests show performance improved by 2 to 4 times. Faster startup, faster game load times with big mod lists, faster map generation, faster world generation and better general ticks per second all get named in the post, which reads less like a feature list and more like a statement that everything got quicker. The studio's own stress test of a late game colony ran 2.2 times faster on 1.7 than on 1.6. For anyone who has watched a huge base crawl at triple speed, that number alone will get attention.
Then there 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. Ludeon is careful to add 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 people have run their own colonies on the new build.
Saves, mods and the old PC warning
The compatibility story is the part most players will care about. Ludeon says 1.6 savegames load on 1.7, and 1.7 saves also work if you go back to 1.6, so there is no one way door. Mods are in similar shape: the vast majority are said to run on 1.7 without changes from their authors, and some will simply show a yellow potentially unsupported warning because the version number moved. Modders are asked to test and publish a version marked as 1.7 compatible so that warning disappears. For a game whose long life rests almost entirely on its mod scene, that is the single most important paragraph in the post.
There is one catch for older hardware. If your PC is more than 10 years old, Ludeon warns that 1.7 may not run on it, and it asks affected players to report in on the official development Discord so the team can look at changes to help. That is a reasonable thing to flag up front, though it will not make anyone with an aging laptop feel better. Engine swaps are rarely free for the oldest machines, and this one is no exception.
What modders get and what testers are reporting
Waylith is not only a speed bump for modders. Ludeon says it allows the latest C# language features, makes it easier to write complex mods without hurting the game's performance, and opens up bigger visual changes and more complex custom effects. More than two dozen modders helped test and share feedback before the reveal, which is the sort of groundwork that explains why the compatibility claims sound confident rather than hopeful.
Early player reports back the headline numbers, with a catch. PC Gamer's Joshua Wolens quotes a Reddit user reporting a stable 120 fps and about 900 ticks per second where they normally see 60 fps and roughly 700, and another player who loaded 1,477 mods and dropped from at least 30 minutes to six minutes and 17 seconds. The same coverage notes complaints that the new build is hungry for memory, with one player describing 12 to 13 GB of RAM used right at startup. Only a couple of reports are quoted, so the honest read is that reaction so far is limited and positive, and that memory use is the first thing worth watching.
Trying it yourself is simple. Update 1.7 is on the unstable beta branch on Steam right now: open RimWorld's properties, pick the Betas tab, choose the unstable branch and let Steam prompt you to play 1.7 Unstable. The main branch that most people play on stays on 1.6 for now, so nothing changes for you unless you opt in, and the post gives no date for the stable release. Ludeon wants bug reports on its development Discord.
The CriticalPixel take
Leaving a commercial engine for one you built yourself is a bold move for any studio, and the receipts Ludeon has shown so far back it up. A 2.2 times gain in a late game colony, a modpack that loads in less than half the time, and saves that work in both directions is the kind of package that makes a risky migration look boring, which is how a migration should look. The studio also deserves credit for telling players what might break, including the old PC warning, instead of burying it.
The part I find more interesting is the last line of the post. RimWorld is not the only game on Waylith, and Ludeon says it is working on something new, with no details and no timeline. That reads as the bigger reason to build an engine in house: it is not just a patch for one aging game, it is a foundation for whatever comes next. Until Ludeon shows that something new, treat it as a tease and not a plan.
For now the verdict depends on how the stable release shakes out. If the late game gains hold on ordinary rigs and the memory appetite settles down, this is one of the more welcome updates RimWorld's mod community could ask for. If you have a colony that already stutters, hop onto the unstable branch, keep a copy of your saves anyway, and tell Ludeon what you find.
Sources
PC Gamer: RimWorld drops Unity for its own in-house engine
Ludeon Studios on Steam: Announcing the Waylith Engine and Update 1.7