How about approaching it from the other side - when a player joins and they're in the arena, teleport them to the lobby. It sounds more logical to me, and even will work when the admin reorganizes the world and moves the arenas elsewhere, for players that have disconnected in the new arena space.
Commit ceabb372f083c9f45ab1c05154c780c5092961ec has all the approved prefabs from the Gallery server. It generates nether forts like this:
![[Image: netherfort5.jpg]](http://mc-server.xoft.cz/img/netherfort5.jpg)
Two things still need to be done: make the prefabs draw their foundations down towards the ground, until the nearest solid block (so that the fort isn't floating) and tweak the probabiilties and sequences of prefabs so that the generator generates longer bridges, less crossings, only a few balconies etc. One thing could be useful, too: add explicit hitboxes to the prefabs, so that a prefab may specify a hitbox different than its image. This should be used by all the "corridor" pieces to avoid corridors-above-bridges.
Commit ceabb372f083c9f45ab1c05154c780c5092961ec has all the approved prefabs from the Gallery server. It generates nether forts like this:
Two things still need to be done: make the prefabs draw their foundations down towards the ground, until the nearest solid block (so that the fort isn't floating) and tweak the probabiilties and sequences of prefabs so that the generator generates longer bridges, less crossings, only a few balconies etc. One thing could be useful, too: add explicit hitboxes to the prefabs, so that a prefab may specify a hitbox different than its image. This should be used by all the "corridor" pieces to avoid corridors-above-bridges.