The RetroArch "Handheld Electronic (GW)" core is used to run a large number of Game & Watch games.
List of games that work with the core "Handheld Electronic (GW)"
But many liquid crystal electronic games are not supported by this core.
To make them work you must use the MAME core.
These games need 2 different files to work: a file of type "rom" and a file of type "artwork".
Place the rom file in .zip format in the \roms\gameandwatch folder.
Place the artwork in the \saves\mame\artworkfolder, files must have exactly the same name as the roms and also be in .zip format.