How do you run run and gun 2 for mame?
Once you have the downloaded rom "run and gun 2 (ver UAA)"
usually identified as rungun2.zip and about 18 megabytes, you also
need to download the parent rom, system GX (a Konami rom) usally
found under konamigx.zip. This rom is needed for all Konami games
to run. Place both files, still zipped, in your rom folder in the
mame directory.