RimWorld developer Ludeon Studios has announced that its sci-fi colony construction sim will move from Unity to the studio’s own in-house Waylith Oyun Motoru in its upcoming update 1.7. In a Steam update, Ludeon stated the game would “look and play exactly the same” while performance improves by around 2-4x.
The switch promises faster startup time, load times with large mod lists, map generation, world generation, ticks-per-second, and “just about everything else.” As an example, Ludeon cited a modpack of 1500 mods dropping from 14 minutes to 6 minutes to load.

Perhaps most notably for the community, existing mods continue to work after the engine switch. Ludeon noted that some may appear as “potentially unsupported” because the version has changed, but will still function just the same. Player saves can also be carried over from 1.6 to 1.7, meaning no progress is lost by updating.
The update is currently available to test through Steam’s beta branch for players and modders who wish to try it before official release. On the announcement’s Reddit thread, users reported improved performance and working mods, though some noted notably increased RAM usage with the new build.
“if your PC is more than 10 years old, 1.7 may not run on it”
Ludeon Studios
The announcement echoes a similar transition a few years ago with Slay the Spire 2, in which developer Mega Crit moved from Unity to Godot following Unity’s attempt to introduce a per-installation fee for developers—a plan that was later reversed.
The more indies that can free themselves from commercial engine software, the better.

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