Well the benefit of Unity and UE4 is that you can get & install plugins that extend the engine with ready-to-use features, like game shells etc.
This Unigine has none of that so you will need to invent the wheel from the bottom.
We all know how it works out with many indie projects, like Police 1013 which even uses Unreal 4 AND has quite a bit of funding, so you can see what kind of budget this engine will require. Nobody is going to make a porn game with an engine that has no benefit.
There is a good reason why GameMaker, Ren'Py and Unity are the leading tools. Godot is on the way but also still requires too much coding.
Ren'Py is even pretty much obsolete, being dependent on an interpreter (Python) that is now out of support. It really should be updated to at least Python 3.8 which will give the interpreter another 4 years of support.