@m1s3rys1gn4l Neo Geo games are considered arcade games in the scope of retropie. Arcade games come in ROMsets. They come in as parent or clone. A parent rom is a full rom dump of a particular version of an arcade game. A clone may be a different version of said game, but the file itself relies on some of the files on the parent, that is basically just the different files from the parent. So the hack may be a clone that is missing files from the full rom to run.
http://choccyhobnob.com/articles/demystifying-mame-roms/
