MarkoH01: Maybe because GOG did not get the update yet. It's THQNordic so not extremely new that updates for their games get delayed. The strange thing is that there was a time were we got quite a few TQAE updates here. I would suggest for you to either contact GOG support about this or (better) contact THQNordic. For now I can only confirm that the game has not been updated yet and it'S quite a wghile sinve they released ver. 1.52 on Steam .... *sigh*
X-com: How did you guess what game he's talking about? Besides Googling it of course
TQ is the official abbreviation for Titan Quest (nealy all forums are mentioning it that way) and when they released the anniversary edition they also refered to it as TQ AE or simply TQAE. It was easy tbh :)
Add to that that I did remember the last update of it being 1.51 - so everything was fitting ;)