The following information is about a MobArena from a previous map. The MobArena is non existant and cannot be found on /ma list. The information is still available for your reading pleasure.
The Pizzeria MobArena was a new MobArena that did not get a chance to be implemented. From the multiple teasers that were shared with the server, it was a Five Nights at Freddy's themed MobArena. It's possible that it could have been singleplayer, however no details about the gameplay were released.