@murgatroid99 I did a little write-up on simple Chaos Functions in [M]. These are functions that are designed to simulate randomness, but intrinsic, drawn from the board state, and computationally efficient.
http://www.fundamentalcombinatronics.com/chaos-functions/
They are trivial to check, but impossible to predict. Compare the chaotic ❋ negative integer to one that is merely a random number -1 through -n, which is statistically trivial (the negative integer has a 1/n chance of being any n.)