Hmmm, I've never seen that error before, but it might indicate that some vital files are missing from the build. Assuming you're on Windows, do you have antivirus enabled, could it maybe have quarantined certain files from the game?
Yes I'm on windows and I'll see if I can figure that out as I had this problem with another game too, the only antivirus is what came with win 10 and earlier versions of the game worked.
EDIT: I found a forum about the issue and it is missing files that should be in the game folders. The files are _renpysteam.pyd and steam_api.dll I guess here is the link to the forum
I've tried one of the downloads and I can't reproduce the issue, unfortunately. The Github thread mentions updating video drivers, but I'm not sure what that could solve as it concerns missing files in the Ren'Py directory. The fact that you have the issue with another game (also Ren'Py?) is however a strong indicator of something interfering on your end. Game optimizers or anti-virus might be the most realistic option, but you already mentioned don't run those.
If you learn more about the issue, I'd be interested to know more about it.
Yeah it seems to be almost random for me on whether any renpy games will work when I download them and redownloading and installing doesn't fix it. I'm not tech savvy enough to figure this out right now so hopefully someone else can help out.
OK so I just went back through to double check I was actually up to date for windows and I wasn't so now I feel like a complete idiot lol. I updated and now the game is running. Thank you for the help you tried to give me and sorry about wasting some of your time.