KiNgBrAdLeY7: What are you all people saying?
That it's not on GOG because the company developing it haven't made a deal with GOG.
KiNgBrAdLeY7: Blame the company which develops the game and complain to them?
Yes! They're the ones who have chosen not to release it on GOG.
KiNgBrAdLeY7: But they DO have a GOG release! And the choices of platform, ends in less than 3 days from now!
No they don't. You're getting confused between the Bloodstained developer and the Curse of the Moon developer. For some reason they don't even seem to be handled by the same publisher.
Best thing to do might be to ask the people who are making you choose to see if you can "wait and see" for your choice for the bonus game (in case something gets worked out in the future).
KiNgBrAdLeY7: Steam already got the store page entry; whatever happened to GOG's?
GOG never had one because it at no point was it going to be on GOG. Apparently Curse of the Moon is a separate game made by a separate team and isn't even included in the contract with GOG.
tinyE: The godless evil immigrants took it Bradley; better go stop them. :P
*high five*