I am hesitant to switch to Unigine from Darkplaces, due to the fact that I am an artist, not a coder.
QuakeC is what Darkplaces engine uses. I can pretty much look into the neatly written code and figure out how it's done, what it's doing and why (not even being a coder). There is also a full source code of the QuakeC game logic for Quake. There is nothing better and easier to learn by example. Huge archive of the QuakeC tutorials also helps a lot.
I have a license for Unigine I won earlier, but I am having hard time using it because I am no programmer. I have no idea where to start. W