Black Ninja has made this nice, straightforward map, which is basically this one room with a tower at each corner. That door close to where we are aiming at in the screenshot leads to access to the upper level at the far end, on both sides.
Well, there is not a lot to say about it really; the weapons and pick-ups are what one would expect. perhaps, and it looks a fine place for a few of us to gather together. It is not particularly huge as arenas go, and it is far from complex, but it looks as if it ought to work pretty well as a place to play, for some fast-paced enjoyment. The earlier screenshot (below) was taken before the weapons etc were added - note the lower ceiling then, too!