Years ago, when I was in college, there was an unofficial club called the "Cops & Robbers Club" that met every Friday night in the school quad. I was walking by one time and saw them, and decided to join in. It became the high-point of every week, something I would look forward to all week long.
We played several games, including the eponymous "Cops & Robbers," a game where most of the players hide, and a few players (the "cops") search them out and attempt to tag them, while surviving robbers attempt to rescue other robbers from the "jail."
We alternated games of C&R with my favorite... good old-fashioned capture-the-flag! Two teams faced off over a center boundary line. When we had enough people, we expanded the boundaries to include quite a large area, which led to small groups breaking off to sneak around and strike from different angles, while others stood guard or patrolled the flanks.
Looking back, I now realize what an enormously primal activity it was, and I miss it terribly. You don't even think about the exercise you're getting when you're running for your life with a flag. Stalking, sneaking, or keeping lookout, interspersed with all-out sprints, really epitomizes Mark's "play" philosophy.
It was some of the most fun I have ever had. Some nights we had upwards of 40 people. It brought out the animal in everyone. I think that's what everyone liked about it; the freedom. You could forget everything; didn't matter who you were. You were just the hunter, or the hunted.
I wish there were still something like this around, that I could join now. I think Mark would wholeheartedly approve.
I met my wife there, years ago. We're talking about trying to organize a group like that together, if we find the right time and the right place.