Popular Steam game abandons Unity for new engine promising up to 4× better performance

What happens when a game developer decides to replace the engine behind its established hit? In RimWorld's case, the answer could be a substantial performance boost.

Ludeon Studios has announced update 1.7, which moves its colony simulation game from Unity to the company's newly developed Waylith Engine. According to the developer, internal testing shows performance improvements of between two and four times compared with version 1.6.

The game itself should look and play the same. Under the bonnet, however, the changes are considerable.

Faster colonies, shorter loading times

In one stress test, a demanding late-game colony ran 2.2 times faster than before. Another test involving 1,500 mods saw loading times fall from 14 minutes to just six.

The improvements extend to startup times, map generation, world generation and general simulation performance. Actual results will depend on individual hardware and mod configurations.

But what happens to existing saves and mods?

Ludeon says save files remain compatible in both directions between versions 1.6 and 1.7. The vast majority of existing mods should also work without modification, although some may initially display compatibility warnings. The new engine also supports newer C# features and makes it easier for modders to create complex modifications and custom visual effects.

There is one caveat. PCs more than 10 years old might not be able to run the new engine.

A second game is already in development

Perhaps the biggest surprise is that Waylith isn't being developed exclusively for RimWorld. Ludeon has confirmed that another, as-yet-unannounced game is already being built using the engine, although further details remain under wraps.

Update 1.7 is available now through RimWorld's unstable beta branch on Steam. Players can access it through the game's Properties menu under Betas, while the standard release remains on version 1.6.

For now, the impressive performance figures are developer-reported rather than independently verified. Nevertheless, replacing an established game's engine while retaining save compatibility is a significant technical undertaking.