Exactly what it sounds like. Auth with up, up, down, down, left, right, left, right, b, a, enter.
Great for a fun second factor. Does not prompt for anything so just enter it and it works...
Make with make.
Based off of https://github.com/beatgammit/simple-pam and https://www.freebsd.org/doc/en/articles/pam/pam-sample-module.html