I kind of found out the problem. I found out that the Mewn Base game wasn't compatible with my windows 10 computer. I'm not sure how to make it compatible. So I was wondering if you know how to do that. I think if we figure out how to make it compatible then the problem would be solved.
So you tried running MewnBase.exe from both the mewnbase-win.zip download, as well as the mewnbase-win32.zip version, on a Windows 10 machine and neither of them would start for you? Do you know what sort of video card your machine has in it?
If you previously tried downloading it via the itch desktop app - try uninstalling and reinstalling the latest win32 version. (Which sometimes fixes a issue with the game sometimes not being able to launch).