Amethyst-Cat apparently erased their github account, but the internet archive still has one snapshot [1]. The pdf link from there redirected to the davidtpeng account, but that github user no longer has a ChessComplexity repo and the internet archive only has a broken snapshot [2].

[1] https://web.archive.org/web/20201226113203/https://github.co...

[2] https://web.archive.org/web/20240316015417/https://github.co...