Writing the editor in 3DGS will be painfull for me.
I just need some open source 3D engine working with C# and able to :
- Have a 3D viewport under some little windows aplication panel
- display 3D models with basic lightening on level
- wirting/reading files
- control some 3D model cursor
- control camera.

It will be lot more easy ot generate levels with C#and easy 3D engine, and save them as files.

3DGS will just have to read these Files and create the level, place entities.