I think someone here, or on the dev's discord uploaded a version from where the game was still closed source quite some time ago.
I'm not sure how much "pre-steam" there is actually.
If the game was on itch during that time and not just patreon stuff and you bought it there, you might have some luck with their app (I can't say much here though, never used it.)
Aside of that, there's really just getting older versions from their github, which go back to when it was made open source I believe and the different releases on steam.
(Unless someone somehow has the specific version you're looking for, although I don't know if anyone still has those

)