Actually with any retroarch emulators, you can already have 1 retroarch file per rom/game and so you can change buttons, ratio or anything you want per game, but I only managed to make it worked with the old way to launch the emulators with es_systems.cfg (not using “_SYS_”).
Here is my solution:
1) You need to create 1 config file per rom using this type of name “rom_name.zip.cfg” (for example arkanoid.zip.cfg) and put them into your roms folder (they have to be in the same folder as your roms)
2) You need to edit your es_systems.cfg by adding one flag into the line that launches your emulator (only emulators using retroarch of course).
Here is the flag:
A real example:
/opt/retropie/supplementary/runcommand/runcommand.sh 4 “/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-fba/fb_alpha_libretro.so –config /opt/retropie/configs/all/retroarch.cfg –appendconfig /opt/retropie/configs/EmulatorName/retroarch.cfg –appendconfig %ROM%.cfg %ROM%” “lr-fba”
It works on my rpi2!
By the way, anyone would know how to add an “–appendconfig” argument into the new _SYS_ command? I tried different formulations, but none of them workded.
I guess we could slightly modify the runcommand.sh file to add a 5th argument in the launch command. In the end we would have something like this:
/opt/retropie/supplementary/runcommand/runcommand.sh 4 _SYS_ fba %ROM% /The/Path/I/Want/