> I'm guessing you're referring to Neogeo games. You need to update your roms (which we > are not permitted to help you with). Your old roms are enough to run the game but not > enough to get it in the Available list.<
Neogeo is one culprit. Seems to be some other stuff too (mostly fighting games). My research thus far leads me to believe this is going to be a pain in the... neck.
Edit: I don't even know where to begin. I don't know what information that was relevant to old versions of MAME is still relevant (the last version I had was from 2011). I don't know whether I should be trying to rebuild what I have or seeking new versions of the ROMs and why files that I have and are recognised in the old version of MAME are "not found" in the new version.