Level editing has never been so much fun: a press of a key allows you to modify the geometry / textures / entities in-game, on the fly. Even more novel, you can make maps together with others online, in the unique "coop edit" mode (!)[/quote:e4522ec9e7]
Not played with it, had a quick look around when evaluating engines fairly recently. It looked like if you wanted to make Cube, it would do you nicely. But again, it was a very brief look.