I think, incidentally, activity on all three sites was waning even before the Orange festival, although that has made it more obvious. We're just not getting the same number of participants these days.
I agree with your points about the problems of updating and my greatest fear of solutions not fitting previuos moves and having to be redone. But I needed feedback like that so as not to make a complete prat of myself by just setting up the game with all of it's woolley thinking. There are other types of cryptic games already played on this server, but I wanted one that had a finite life span. There is still an empty game slot.
[Darren] Someone needs to do a good, solid corpus-based statistical study on activity rates in the Morniverse. I'm sure it would make a good PhD topic. My impression is also that activity has declined, but it was less busy than now when I first joined eight years ago (bloody hell, eight years). In those early days, fresh with the joy of discovery, i can remember having posted the last move in every game on York and MCiOS, and being quite at a loss for what to do next once I'd done it. Especially on weekends. In retrospect this was a bit rude, but I was immature and callow even in those days. :) I find that nowadays I tend only to post in a small subset of games and even when bored am unlikely to stray into the others. Maybe other people have gradually settled into a similar pattern.
[Projoy] I certainly have settled into a similar pattern, though I'd like to think that's because I'm less obnoxious now. I'd say the most concerning trend is the seeming lack of interest in the game of Mornington Crescent itself - our one token game here, for instance, is crawling along quite pitifully, and Long Games all over the Morniverse have slowed to the pace of Jeremiah Snail, the 1956 All-Dorking District Champion.