Larpers would pay big bucks to run around a place like this shooting paintballs or airsoft at each other.
Set it up so the above ground barracks has some nice PC/Consoles to play with in the evenings, some hot pockets and Mt. Dew for breakfast and let them larp all day with their buddies for $300/person/day.
$400 and you'll throw in a free tetanus injection.
That place looks like an OH&S nightmare. You just need one fat kid to fall down the main shaft and things get real quick.
Yeah, this seems to be the main issue with this, fixing it up to be in compliance with a myriad of either business/residential regulations seems like it would be both a giant headache and a giant cost.
Set it up so the above ground barracks has some nice PC/Consoles to play with in the evenings, some hot pockets and Mt. Dew for breakfast and let them larp all day with their buddies for $300/person/day.