Oh man, I instantly purchased here because I wanted a DRM-free version of this beautiful game and didn't notice that the download isn't even the game itself but only an artbook. The description "A downloadable game" and "Get a Steam key and the official artbook with your purchase!" seem to imply that I get a Steam key in addition to the game download here on itch.io (quite some developers do it that way). The Steam version itself seems to be ridden with SteamworksDRM (it forces me to use the client to run). I would recommend to make it very clear that purchasers won't get the game itself here on itch.io. The way it's written now can easily lead to misunderstandings.
Nice to see the responsiveness and accommodation, but I'd suggest to also consider releasing a DRM-free version here. I, for one, am really interested in this game, but any price is too expensive for a DRM-crippled game for me. ("Defective by design")
Edit: I just realised the game is available on GOG.com – thank you! :)