This is a thought provoking card game which is an implementation of a question in the Regional Mathematics Olympiad, 2016: https://brilliant.org/discussions/thread/rmo-2016-delhi-region/
The premise of the game is:
The user will choose 5 random cards and then will select 1 final card from the selected cards. The rest of the cards will then be arranged in a permutation computed by an algorithm. Since I know the algorithm, I will be able to figure out the final card just by looking at how the other cards are arranged.