Cube engine (MAJOR LEVEL DESIGN ADVANTAGE)

If somebody doesn't know what it is (and I think it's probably the majority), please check out the game "Cube 2: Sauerbraten" on sauerbraten.org.
It's a free simple, multiplayer, open source, fast paced first person shooter. But that's not really what I'm so excited about.
It's the game engine. The map editor in that thing is just incredibly easy to use and it's probably the easiest 3D map editor out there. You really can do some amazing things with just a few clicks.
The maps are saved in an .ogz format.
If it were possible in any way to make that format compatible with Unity3D, I'd be most thankful, since that would be such a great step forward in terms of level design.
I really do hope you give this some consideration, because I can't do more than ask you to try it out, you won't regeret it. Side note: I'm NOT advertising anything. =)
Cheers, TW

PS: Some screenshots.










EDIT: I should probably add that the license for this engine is totally free for personal and commercial use.