This has Peter Norvig sudoku energy, in that it describes a game that is tricky enough for humans to solve that it's become a whole pastime, but is a trivial so

This has Peter Norvig sudoku energy, in that it describes a game that is tricky enough for humans to solve that it's become a whole pastime, but is a trivial solver away from reliably defeating, and with a tiny amount of code. Once you see what they're doing with this, you're like, oh of course. Very cool.