On the Batocera, Retrobat (since 1916 beta 5) and Retropie frontend, it is possible to create collections that bring together several Roms and appear in the Frontend as a fully-fledged system
To build these collections you can do it via the Frontend interface, or with ARRM (since 1.8.6.3) see download link: http://jujuvincebros.fr/telechargements2/category/11-arrm-update-correctif
A collection is actually a file named 'custom-%NAME%.cfg ' (where %NAME% will be the name of your collection) which is in this folder:
The file is then completed with the path of the Roms that we want
Example under Batocera with the collection “ custom-shmups.cfg ”
/userdata/roms/mame/1941.zip /userdata/roms/mame/agallet.zip /userdata/roms/atari2600/galaxian.bin /userdata/roms/neogeo/sonicwi2.zip ...
Example under Retrobat with the collection “custom-shmups.cfg”
./roms/mame/1941.zip ./roms/mame/agallet.zip ./roms/atari2600/galaxian.bin ./roms/neogeo/sonicwi2.zip ...
Same example under Retropie
/home/pi/RetroPie/roms/roms/mame/1941.zip /home/pi/RetroPie/roms/userdata/roms/mame/agallet.zip /home/pi/RetroPie/roms/userdata/roms/atari2600/galaxian.bin /home/pi/RetroPie/roms/userdata/roms/neogeo/sonicwi2.zip ...
If your Batocera/Retropie is not connected to the network, all you have to do is create your custom-%NAME%.cfg file locally then, once completed, copy it to the correct directory on Batocera/Retropie.
You can :
The files are added to the collection.
Remember to activate the new collections created by going to your Batocera/Retropie in the appropriate menu. Existing collections will appear among the list of systems.