I have to go to bed now. I suppose I could start the games up again, and leave them up until I wake up again and start working on the server - but I don't see the point of that, since the rules would require a pause of up to 24 hours after this, so the game would possibly not even be unpaused before I have to take it down again.
The reinstallation and rebuild of everything may take me 1-2 days now that I've had time to look at how much I have to redo, so for good measure I will say that the game may be down for the entire weekend. If everything goes well, it'll take far less than that - but after the nightmare I've gone through tonight I'm not placing my bets on that.
(For anyone who may be interested in the technobabble it was the attempted move of a WSUS database that failed, which led to a cascade failure of several services, rendering the server more or less inoperative with Windows Installer as the final service that failed and I had to take ownership by force of several registry entries which really shouldn't be necessary just to install stuff. I don't want to leave my server in that state, so it needs to be reinstalled.)