I don't mean to sound mean or disrespectful to what you did, and I'm not being nasty, but just as a comparison, when my DD turned 12 (which was November, so had JUST started at secondary school and most of the parents hadn't met) we did treasure hunt/capture the flag in a local wood.
DD sent out all the invites re social media. I made her include my phone number and urged parents to get in touch. Most didn’t. I didn't know most of the people invited. It was the first party where she'd invited boys. All said they were coming and then all except 1 dropped out on the day because it clashed with some football something.
I did ‘scoping’ at the area at least 4 times (walking the route, picking things to use as ‘clues’ and then going back to check nothing had changed as it was autumn and leaves were changing colour and falling off trees). I walked there with DD because her group was going to do the walk “backwards” (it was a short, circular walk and the treasure hunt ended in the middle, with two groups starting from the same point, but one following one half of the circle and the other group following the other) and I wanted to make sure she knew the way.
I went there early on the day of the party to set the clues up for the groups to find.
At the party, DH and I carried folding chairs, blankets and picnic including cake to the central point. We dished out prizes, sorted food. Had to deal with one of DD’s bfs who isn’t very out-doorsy and wasn’t enjoying herself much (and was stopping others from getting stuck in).
During Capture the Flag 2 girls (who I’d never met before and wouldn’t recognise) got themselves lost, and DH went off into a total panic, shouting at all the other children (cos that was helpful!) 
They did eventually turn up, but we'd both aged about 10 years by then.
Oh, and another of DD's bfs lost her phone.
So when you say Aibu to say never again?? about what sounds
like a not very eventful sleepover, I'm not quite sure what to say in response.