Damn, I've just been on his twitter and he made an explanation a week ago as to why the game isn't on GOG. So the new store isn't GOG it seems, f**k.
Actually it was just a joke from me and I still expect to see the game on GOG as he also said "We would still like to be on GOG if they change their mind!".
That said, in december when Zachtronics was looking for an alternative to GOG after the reject, he mentionned Humble and itch. He choosed Humble because... obviously... that's some sort of Steam+ with possible DRM-free installers sometimes. But if itch comes also, it can be "good enough" for me.
Or, hopefully, GOG realized their mistake and finally the game will come here ?
But... itch is really that much better than Humble ?