I'd play on SkyBlock world more than I'd wanna' touch Fort World. Same restrictions as Freebuild. No IDP protection, no TinyWE, no flying.
You could play a single player world, or invite up to 4 friends per one world.
(/start -player 1)
(/start -player 2 -username [name] -u [name])
(/start -player 3 -username [name] -u [name] -u [name])
(/start -player 4 -username [name] -u [name] -u [name] -u [name])
[Shorted player to p, and username to u]
And if you want to start over
/endworld
Which will warp you back to the home base
Home base will list your objectives:
tba
If you complete all objectives, you have a staff come check out what you've done, and maybe a reward will be given (I think this would be cool, because the objectives are hard at times)