Hey all,

I teach in a high school IT lab 11-12 grades.
I like to have a game for them to relax with but is also useful.
I am looking for a game that is multiplayer, persistent, requires cooperation / team work, some competition is good, G or maybe PG rating, local server, requires obtaining skills to support the rest of the group, possibly some sort of economy.
I have run a MineCraft server which works ok but I find that not many can afford an account and I will not run a hacked game. It also lacks some of the need for teamwork even with mods.
I'd like an RPG I think, it has to be LAN based as I have to keep them blocked from off-campus contact.
Not gross, horror, FPS, bloody, sexual content .....

I continue to search google but I am hoping someone out there understands what I am looking for and may have suggestions.

I have seen items sometimes on Humble Bundle that go for a few dollars ( not that MC is all that expensive but it is for some of these guys ) free is always good but not expected.

OpenSuse 42.3 and 15

Thanks for your time.