https://blog.faceutil.com/2017/05/05/mame-%ec%94%a8%ed%8b%b0%eb%b4%84%eb%b2%84-city-bomber-%eb%a7%88%eb%a9%94-%eb%8b%a4%ec%9a%b4-%eb%8b%a4%ec%9a%b4%eb%a1%9c%eb%93%9c-down-s/