Re: Genesis games are Notepad files.

First, if using Windows, ensure file extensions are enabled to be shown in Windows Explorer if not already. Then you should see the extensions of the ROM files are ".md" files. This is misleading and incorrect, as .md refers to a text file with Markdown formatting, hence why your system is opening it as a text file. Instead, rename the extension to ".smd", which is also valid, but explicitly refers to a SEGA Mega Drive / Genesis ROM instead of a Markdown file, and your system shouldn't try opening it as a text file.

They're just Notepad by default.