It seems Godot is getting quite a lot of traction these days (I see a lot of "Godot introduction for Unity devs" videos these days). The Godot engine might be

It seems Godot is getting quite a lot of traction these days (I see a lot of "Godot introduction for Unity devs" videos these days). The Godot engine might be less complete than Unity, but calling it immature is a bit strong IMHO. For devs having been burnt by a proprietary engine, namely Unity, the Open Source aspect alone is a good reason to switch. So Godot is bound to get far more users, and consequently, develop and improve significantly.