[QUOTE=Thatman84;53637]Tatsuya79 How do you do it please?[/QUOTE]
Copy the genesis_plus_gx_gg_libretro files in your core and info folders.
Make a playlist for your GG games that will use this core. (or load manually if you don’t use playlists)
In the config folder create a “Genesis Plus GX - Game Gear” folder. In this folder create a text file named “Genesis Plus GX - Game Gear.cfg” with:
video_shader = “:\shaders\handheld\console-border\gg-4x.cgp” (put your own path) aspect_ratio_index = “1”
It should get applied on start if you’ve got “Load overrides files automatically = ON” in Retroarch Settings->Configuration.