Another promising game engine with lots of big features is Flax, available free with the source available (but not Open Source) has a huge new release out with improvements to their Linux support.
The big highlight for us here of course is their new Linux Editor, so now you can build and export games using a full Linux development environment. Using Vulkan for the rendering this is the full experience they say with "live scripting with C++/C# hot-reload, Visual Code integration, scenes editor, game cooking, terrain editing, foliage editing, and much more" giving it feature parity with the Windows editor.
Lots more is new with this release including low level networking improvements, Spline tools, lots of goodies added to the Navigation system like multiple navmeshes support, enhancements to their visual scripting system, a new third-person shooter example project, lots of editor upgrades and plenty more improvements elsewhere.
Check out the Flax 1.1 release notes.