https://blog.faceutil.com/2017/04/30/mame-%ec%97%90%ec%9d%bc%eb%a6%ac%ec%96%b8-3-the-gun-alien-3-the-gun-%eb%8b%a4%ec%9a%b4-%eb%8b%a4%ec%9a%b4%eb%a1%9c%eb%93%9c-down-%eb%a7%88%eb%a9%94-%ec%98%a4%eb%9d%bd%ec%8b%a4-%ea%b2%8c/