1. Install MESS-Libretro on RetroPie
If you would like to add some more obscure consoles or computer systems like for instance the Interton VC-4000, BBC Micro, Super Cassette Vision, Adventure Vision, Channel F, Bally Astrocade and many others onto RetroPie, then MESS (Multi Emulator Super System) would be your answer. First read this Wiki carefully:
I installed lr-mess (lr=libretro) from the experimental section in RetroPie-Setup which took about more than 2 hours on my Raspberry Pi 2.
After restarting RetroPie I couldn’t find any MESS section in the emulationstation menu. That’s normal because you have installed only MESS and not any systems yet.
2. Add a system (bios & roms)
As an example I use a system which uses a BIOS and of course the roms itself. For the BIOS and roms files lr-mess uses .zip extension, so for instance the BIOS of the Super Cassette Vision has to be scv.zip and has to be in your roms folder, not in the BIOS folder.
Don’t unzip these files!
The roms do also need to be in the roms folder as well but in a directory the system is called, so for this example scv.
So you have this:
scv.zip -> BIOS
scv -> roms directory with the zipped roms inside
If you don’t know how the system has to be named or is supported by MESS, you can check this website here or in your directory:
3. The config options
To get lr-mess running you need to add a new folder scv of the system and add two files:
In emulators.cfg you add these lines:
lr-mess="/opt/retropie/emulators/retroarch/bin/retroarch -L /opt/retropie/libretrocores/lr-mess/mess_libretro.so --config /opt/retropie/configs/scv/retroarch.cfg %ROM%" default="lr-mess"
In retroarch.cfg you add these lines:
# Settings made here will only override settings in the global retroarch.cfg if placed above the #include lineinput_remapping_directory = /opt/retropie/configs/scv/
put them both here:
Be sure that all these config files have permission 777!
4. Add your new MESS-system for emulationstation
To see the section of the system Super Cassette Vision on the emulationstation menu you need to add a new system. Add these lines in the es_systems.cfg, which is located here:
<system> <name>scv</name> <fullname>Super Cassette Vision</fullname> <path>/home/pi/RetroPie/roms/scv</path> <extension>.zip .ZIP</extension> <command>/opt/retropie/supplementary/runcommand/runcommand.sh 0 _SYS_ scv %ROM%</command> <platform>scv</platform> <theme>scv</theme> </system>
5. Add a theme for your system
For MESS I modified an already existing carbon theme called mess and replaced just the system.svg with the proprietary system logo. You need root or you can use File Manager in RetroPie.
6. Test the system and map your controller
After restarting RetroPie you finally should see your new system section in emulationstation, in this example the Super Cassette Vision. Choose a desired game title and lr-mess should show up and load it.
You can map your controller while pressing the TAB key, then go to Input (this Machine). Be aware that not all systems work properly, check here (red ones usually might not work properly).