I have played many maps and I must say this is probably my favorite map so far when it comes to arenas. Great work!
The only thing I think you could improve on is the shop. Maybe use redstone to automate the buying to ensure people don't cheat. But then again, if people wanna cheat they can do so anyway by just switching the creative mode so it might not be as useful as I imagine.
I didn't automate the shop because of a few reasons. There was a lack of space, all that redstone would make the world lag and, well, I'm no redstone genius so I didn't really know how to automate it. But thanks for the feedback though, I greatly appreciate it!
I played with this world It was very interesting.
However, in order to allow more people to play comfortably, I would like permission to translate this distribution world into Japanese and make it easier to play and distribute. Of course, DL will display as the reprint source.