A slackline is like a tightrope...but the part you walk on is wider (sort of like a heavy duty nylon ribbon.) You string it between two trees (it can be close to the ground so noone gets hurt if they fall) yet it’s still challenging.
Here’s a wiki link:
http://en.wikipedia.org/wiki/Slacklining
My son’s always been an “outsider” too. He went through a stage where he played video games, and we still have the systems, but his time became more precious (through college and now grad school) and he just didn’t have time for video games.
He’s always rather been outside playing football, baseball, “war games” (how is it fun to get hit with a paintball and get a big bruise???, LOL) and now he’s spends spare time boating and spearfishing w/his dad.
I’m so glad his “addiction” to video games was shortlived, I know a lot of college kids who get totally sidetracked from their studies because of the amount of time they spend playing video games.
My son would love that!
My kids are just like your son. They haven’t really “played” unless they have something to show for it, like a bump, bruise or scrape.