My mistake, I have the registry files for creating them on the account you add them to the registry in but they don’t work in every account once they’re added. So here we go, you can use this one as a template. Just copy and paste it into a text file then rename the extension from txt to reg, double click it in install the registry keys.
Win 10 SNES (Super Nintendo Entertainment System) file extensions
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\SOFTWARE\Classes.smc]
“(Default)”=“SNES”
[HKEY_CURRENT_USER\SOFTWARE\Classes.smc\OpenWithList]
“a”=“C:\Program Files\RetroArch\retroarch.exe” -L “C:\Program Files\RetroArch\cores\snes9x_libretro.dll” “%1"”
[HKEY_CURRENT_USER\SOFTWARE\Classes.sfc]
“(Default)”=“SNES”
[HKEY_CURRENT_USER\SOFTWARE\Classes.sfc\OpenWithList]
“a”=“C:\Program Files\RetroArch\retroarch.exe” -L “C:\Program Files\RetroArch\cores\snes9x_libretro.dll” “%1"”
[HKEY_CURRENT_USER\SOFTWARE\Classes\SNES]
@=“Super Nintendo Entertainment System Game”
[HKEY_CURRENT_USER\SOFTWARE\Classes\SNES\shell\open]
@=“Play”
[HKEY_CURRENT_USER\SOFTWARE\Classes\SNES\shell\open\command]
@="“C:\Program Files\RetroArch\retroarch.exe” -L “C:\Program Files\RetroArch\cores\snes9x_libretro.dll” “%1"”
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts.sfc\OpenWithProgids]
“SNES”=hex(0):
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts.smc\OpenWithProgids]
“SNES”=hex(0):
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\ApplicationAssociationToasts]
“SNES_.smc”=dword:00000000
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\ApplicationAssociationToasts]
“SNES_.sfc”=dword:00000000