Open Retroarch on your gameshell
Select Load Cores
Select Download Core
Select 2048_libretro.so.zip
Quit Retroarch
Connect your device to your gameshell with SSH
Lets move the core to the emulators folder.
(If you use another folder to save your downloaded cores navigate there)
mv ~/.config/retroarch/cores/2048_libretro.so /home/cpi/apps/emulators
Make the .sh file
nano ~/apps/launcher/Menu/GameShell/2048.sh
Add:
retroarch -L /home/cpi/apps/emulators/2048_libretro.so
Save and quit
Move the icon to ~/apps/launcher/skin/default/Menu/GameShell
cd ~/apps/launcher/skin/default/Menu/GameShell/
wget https://raw.githubusercontent.com/ocr-junky/GS_Icons/Icons/2048.png
Make sure the icon has the same name as the .sh file. In this case 2048.png
Reboot and have fun