Firstly, I am sorry for the delay in replying to you. We were unaware there was a BPM Sub forum, we were only told about the announcement post in general. I'll be keeping a much closer eye on here moving forward.

So, on to your question. The honest truth is we were only approved for GOG a few hours before the PC and Xbox One launch of Battle Princess Madelyn. This left us very little time to prepare things sufficiently.

The team at Causal Bit Games are working on a few bugs and patches right now, but hopefully we'll be able to integrate GOG achievements at a later date. :)