Wym? Does Notepad say "file cannot be opened" or something like that? When I made this game I was still using Windows 10 and it was fine, my best guess is they "updated" Notepad again and made it worse. Well you can always edit in a different text editor, or edit .txt files and then "save as" and change the file ending to .hi216. They're just basic TXT files with a different file extension to seem fancy.