Thee Realm of Nothing
This map was made by Pimp before his recent departure (for a while) from NAB, so Mikesmaf was the one who showed me round. This screenshot is not very representative of the arena as a whole - because it is made up of lots of rooms, and lots of corridors, in plenty of different styles. So, it takes a while to get your bearings here, and as a place to play, it has the problem, shared with a few other maps, that if you are trying to have a fight with two or three other people, they can be hard to find - and each time one of you does the zero-health boogie, the battle is effectively over until you run into each other again!
That said, there are plenty of fun features here; a small secret room, linked to a second small secret room and a secret corridor (with some secret stairs), which leads to a larger secret room, containing... nothing much, actually... And there is an express elevator that boosts you up half a mile, to another playing area - but as the platform stops well above the floor, you can't use it to go back down on. It's fun to jump down, overtaking Mighty Mo balls as you go, though, and the jump doesn't kill you... however, the sudden stop at the bottom does, heheheh!
So, it is large, it is fun, and it is more for exploring than serious playing. I am not sure if it is being generally released at this stage, but check around! A revised version might get a slightly higher rating, but at the moment I'm feeling a bit harsh, ratings-wise....