Using blender as a custom editor for a game engine?

I am currently writing my own game engine and I was thinking if I could use blender for the editor. Can I completely customize the editor? And with completely customizable I mean that I want to create my own game engine specific toolset so that I can place scriptable entities inside blender.

Do also know if it is possible to render directly into blender? For example at the moment I render directly from OpenGL into GLFW and I want to render into blender instead.

What your asking is a little unclear…maybe it’s just I’m not as advanced enough, but here’s what I think…Blender, as you know, is mostly open source, so you can take a look at the code and use that…I don’t know what you mean by “use blender for the editor”, but the BGE IS the editor…Yes, you can customize it because the Blender Foundation pretty much gave you the code for free… I think what you’re really looking for is to create an ADD-ON that allows you to change the interface and the toolset, then implant it into blender Game Engine…that is a yes

I believe you can, as long as you can import it with the correct file format…