Somewhat embarrassingly, I've spent about 2 hours trying to get galaga to work on my version of MAME.
I am using a MAC. I have .183 downloaded as well as the front-end programs OpenEMU and Mame OS X.
Here is a screenshot of my roms folder:
https://www.dropbox.com/s/0ldz1i783z...01.53.png?dl=0
In terminal, the romset shows as good, as you can see below
Erics-MacBook-Pro:mame ericlinder$ ./mame64 -verifyroms galaga
romset galaga is good
1 romsets found, 1 were OK.
Erics-MacBook-Pro:mame ericlinder$
But when I go into the executable, I get an error: "The selected machine is missing... " (I'm not able to take a screenshot of that for some reason)
I'm hoping the solution is somewhat simple? Thank you SO much!!
Edit: So this is interesting, I downloaded a front-end for Mac and galaga works on it - but what's odd is that the front-end points to the same name directory .... ?!