This was in fact the first custom map I played. Basically is a broken layered ring around a Quad. There is the odd point here and there where you can get a bit stuck on a wall, a clip brush would have fixed this. Only real gripe about this map is the connection from the Red Armour to the window below is a bit weird.
The readme says up to 6 players, 2 is enough, 3 is fun!