[reactordev]

It's trivial to render to a texture (framebuffer) using a separate camera matrix and shader pipeline to make a minimap. It was in 2015 as well. Rendering to two separate windows is also trivial if you're rendering to textures first instead of directly to the backbuffer. Making use of those two windows is not trivial.

All in all, SupCom had issues with the number of units on screen (or in general) and would slow down considerably under heavy troop battles. Still, it was awesome.

Ever since 2006 or so it's been standard practice to break up the rendering pipeline and render to textures that you would combine in various ways in post (deferred shading came about around this time). So it's not an entire graphics engine process. It's just simply a render target.