This is a new map by Blades - and, as you can see, rather a good-looking one. It is inspired by SLAM's Red Psi arena, but is not a direct copy or "retex" of it - rather, a tribute. Not that SLAM is entirely happy, as he had been thinking of doing either a blue or green sequel himself! And the name is a little misleading, as the shape of the acid-bath here is not the shape of the Greek letter "psi", so really it ought to be "Blue Cross"! When you download this map, be aware that you need the incredibly tiny, less-than-one-kilobyte Blades Unreal Ed texture file as well, to put in your NAB textures folder of course; when other people offer this map file, I hope they will zip it in with it, to make things simpler!
However, for a new mapmaker this is pretty good stuff. Blades has been able to resist most of the temptations that new mapmakers fall prey to, and delivered a good-looking, simple arena that works pretty well. That lower walkway can be treacherous, with bits of path that flip over when walked on, which is a nice touch, and the lighting, while a bit dark, is certainly atmospheric. As far as I can tell, the cylinder hanging from the ceiling is just decoration, but it is a good touch, and this is a map that you could have a fine battle in. Which is the main thing, I think...