Debug is mainly used to test new updates before they are released to the official version. Everything is tested here, but sometimes aspects are exclusive. This usually means that they were cancelled prior to the update or the servers simply haven't been updated to reflect these changes.
Data does save here but doesn't carry over to and from the main game.
You will be permanently banned if you break any rule here. All bans here do not carry over to the main game, so if for whatever reason you are banned, it's not the end of the world.
The Debug game can be found here.