After entering Early Access in 2014, JIW-Games have been rewriting their open world sandbox game Rising World to move away from Java and instead use the Unity game engine.
They actually announced this back in 2019, as part of a post mentioning how changes to the Valve algorithm for showing games had dropped off their store page traffic dramatically. They said about wanting to rework a lot of it and Unity would help them achieve this.
Back in December they finally showed off the result of their efforts, with a massive overhaul available in Beta that's now using Unity and they're continuing to support Linux.
If you wish to try the new Beta, on Steam you can opt into the "unity" Beta which has a description of "New Version Preview". Currently though, they say it's a "demo" as it has very limited features and just meant to showcase they are genuinely working away on the big overhaul.
The good news is that they mentioned how many of the core mechanics are integrated or almost ready, so hopefully they will start doing more regular updates now. On their official forum in early January 2021, they mentioned construction and multiplayer currently being in progress.
Good to see they're still going with it after so long, especially as the original Java version was quite highly rated by players.
Find Rising World on Steam.