Well, we were down through the month's passing, so to make it sound more dramatic, I've written the subject that way.
What a stupid mistake. I'm sorry. I transfer all the sites - 193 sites - from the old server to the new server. Of all of those, two sites failed and I hadn't noticed because cPanel/WHM didn't show me any fatal errors. Numerous little inconsequential errors, but I checked nearly 100 sites by hand after the first batch, so I spot-checked the second batch, and hence missed that forum.simutrans.com didn't get transferred. Everything else did, except one other tiny site.
And I've been busy - I usually check the forum every day, but sometimes it's 2-3 days or so between coming here.
So I dropped the ball. I'm really sorry, guys. But the good news is that we're back and everything should be here.
Thanks to Yonatan for poking me on Facebook.