I'm wondering, perhaps Steam has to be installed for it to work. I never had any trouble running it outside of Steam, but maybe it's an issue when there is no Steam on the computer. I will have to test that ... that could effect my other games too.
Just to check, do you have Steam installed on your computer?
Okay, I think I've figured it out. I just uploaded a new version of the game. The filename ends with "_ITCH.exe" - I have removed the old version so that should be the only one there. If you download the new version it should not try to connect with Steam.
Sorry for the inconvenience! Thanks a lot actually, I was not aware of this issue. If you would like, I can send you a Steam key for the game too. But let me know if the issues is resolved on your end first.