@dankcushions I was able to get Galaga to work by disabling the video driver. Apparently it was using a proprietory driver. That said I cannot get the sound to work. I will do a separate post on that issue.
@johnes
Broadly speaking if you have a Pi3 the mame-2003 emulator is a good bet with the 0.78 romsets.
If you want to stick with the 0.375b then I'd use lr-imame4all - not least because it will allow all the Retroarch functionality as well as easier controller file config.
You may want to check your system specific retroarch file isnt holding a mass of non-required configs now, there is usually just 4 or 5 lines in there.
A bit like this: http://pastebin.com/n5FbDBUK