I was planning to buy the game during this sale on GOG, but then I've realized the lack of a few features that are available on Steam. First, there are no achievements on GOG, which is already very odd, but then what really surprised me is that there are only 25 languages available on GOG while Steam has 26 -- the one missing is "European Portuguese." To make matters worse, on Steam there is full audio for all available languages, while GOG only has full audio for English.

What's going on here? Are the setting really that different? And why would they offer less features if they have already implemented them on Steam?

The whole thing doesn't make any sense to me and now I'm reluctant to buy the game on GOG as a matter of principle, since it seems like a lesser version of the game.