https://blog.wongcw.com/2019/06/28/%e3%80%8aflappy-bird%e3%80%8b99%e4%ba%ba%e5%90%83%e9%9b%9e%e7%89%88%e4%b8%8a%e7%b7%9a%e6%89%93%e9%96%8b%e7%80%8f%e8%a6%bd%e5%99%a8%e5%b0%b1%e8%83%bd%e9%81%8a%e7%8e%a9/