UPDATE: Relocating the home folder to a USB flash drive is a much better option.  Found that folders don’t ln -s very nicely.  Editing fstab and referencing the drive by UUID is the more elegant solution.  Added bonus, can power down, plug into a PC and update the games more easily.

I’ve been playing with RetroPie this weekend on a Raspberry Pi 3.  Using iBuffalo controllers I purchased from Amazon.  The micro SD card I am using is only 8GB, however all the guides I’ve seen list a difficult method for installing games to an external USB drive.  RetroPie simply runs a Linux distribution, and as such has access to all types of fun file tools.  In this case, the easiest one I’ve found is to use symbolic links to the external drive.  This takes a little bit of work setting up ssh access and some command line kung-fu, but it is basic stuff.  Retropie expects to find the files for each system in ~/RetroPie/roms/{systemname}.  By default the first external drive is mounted at /media/usb0/.  If we take this information we can “ln -s /media/usb0/{systemname}/* ~/RetroPie/roms/{systemname}/”.    As far as the operating system is concerned, it will check the default folder and treat the files as if they were where they belonged.   All my games are already sorted by system so I just have to link each file to the default folders.

Added bonus, it’s also possible to install Kodi in RetroPie, making this an all in one system for retro gaming and media playback.