Then again, that is a bit of a preconditioned structure to work by (edit: and so weakens the "value" of improv therein) I see improv games as amazing practice as well great fun packed with entertainment value.. but it's still not as raw as you can get. Not to diminish it or devalue things like Harolding, but working the crowd for example is a very difficult form of improv in stand-up and it is rarely ever a killer performance... in fact I can't think of any really "homerun" crowd-working because there are just so many wild factors and risks. However, that to me is an example of ultimate improv, not just acting without the script, but without the set and director too. But that aside, you're absolutely right that improv can really end up anywhere, and that's really the fun of it. I'm personally real into jazz music, and seeing a live performance where you know (or better yet, aren't even sure) that they're improvising is a thrill man, it's a ride.