I wrote a front-page review regarding "Mob Rule", the latest release. Until today, a couple of other reviews have been written, but mine remains with the most people agreeing to it. However, a newer review with only one person agreeing has suddenly become the "most helpful review" - why?
Note; I do not desperately want to see my review remaining the "most helpful one"; I do realize that other players may enjoy games I don't. I'm just curious as to how the system determines the "most helpful one".

It's possibly because a number of people disagreed with your review. Whereas the current 'most helpful' review has 100% agreement. Even if that's all from one person. But yeah, that does look like it's going to need some more work as it doesn't make sense as it is.

I thought there was also some degree of human involvement in deciding what is most helpful

Human involvement? I thought we were all androids!

It's pretty obvious there is; but if not agreeing to a review also contributes to its "helpfulness value", then the number of people not agreeing should be displayed as well (like on Amazon reviews - "18 of 25 customers thought that this ...". Everything else would just be misleading.

That would make matters a lot clearer and more unbiased as a result. Right now it just looks like negative reviews are being pushed further down the list for no reason, and that could reflect badly on GOG.