Hi, I had the same issue with the file error, and was able to solve it by just deleting the README.txt file entirely (remaking it didn't do anything); I've been playing for a bit and nothing seems to be broken.
I didn't try compatibility mode or have your issues there, but if you right click on the .exe you should be able to select Properties, go to the Compatibility tab, and uncheck "Run this program in compatibility mode for... (whatever windows)".
If your progress is still gone after that, I think from trying to troubleshoot the file myself earlier that save data might be stored in hungrymermaidcruise.ini, so if you have a copy of that file from an older version of the game you can try renaming or deleting the .ini with the same name that comes with the new version and pasting the old .ini file into the new game folder. I can't guarantee that'll work either, but I think it would be worth a try if disabling compatibility mode doesn't fix everything already (also, just in case: if after everything you're still missing the other modes, I would make sure you didn't redownload the demo version by accident).