I followed this guide and everything works really well EXCEPT when trying to open the game as a non-steam game (to use later in Gaming mode). When I open PokeMMO.sh as a non-steam game, it's as if the game cannot find/load the roms even though they are in the roms folder. When trying to add the roms via the in-game client management, I get "File selection was cancelled." Has anyone found a solution to this?
Here is the Steam shortcut in case you are wondering.