Perhaps a few details wouldn't go amiss in case something similar happens to them.
Playing the 10-letter game yesterday afternoon (local time) in the chi.lexigame.com site, I noticed that the Forum section of the page had been replaced by a warning from 'Bitninja.co.io' (or something like that). I clicked on the 'Full Page' button to return to the normal screen and I saw that that was the same.
I returned to the 'Full Screen' mode and found that the game had disappeared completely to be replaced by 'bitninja'
Using the icon on my 'favourites' bar, I was able to get back to Chi on the chihuahua-puzzle.com site. This was working normally but there was no forum.
At this point I e-mailed Alan; I'd assumed, wrongly, that the Chi site was infected by a virus of some kind. Alan replied to my email assuring me that there was nothing wrong with the site, that everything was running normally. He suggested that I reload chi.lexigame.com. but I was unable to do that.
I did all the usual things to my computer - system restore and a quick McAfee virus scan, which reported no problem
Later that night I played the Challenge game with chihuahua-puzzle.com. I was still unable to open chi.lexigame.com (Bing actually informed me that there was no such website!)
I played the new standard game; logged off and on a hunch about 30 minutes later opened the site again to find that everything was back to normal - both websites, complete with forum, were up and running - certainly not because of anything I had done, and, Alan assures me, not because of anything he had done.
Perhaps some forumite who speaks Computerese knows what happened - I sure as hell don't.