@Darksavior One other potential problem with /tmp/retroarch came to my mind. If it doesn't exist on boot time because RA deleted it, the auto-mount via fstab will fail. After one successful mount however, it will be protected from deletion by the mount.
Thus, the safe sequence would be:
Create the directory via mkdir -p /tmp/retroarch Edit the fstab like described above. Reboot.Then, the directory will be there on boot time, the mount to ram will happen, and prevent deletion until shutdown. Rinse and repeat. :)
This isn't necessary if the whole /tmp is mounted to ram, of course.