You and a dealer each pick choose one of the first 10 cards. Each card tells you how much
to hop forward to the next card. The trail stops when there are no more cards to reach.
The trick is that the dealer chooses a card that finishes at the same place your card
does. Once you've played a while, type data for a running summary of your games. If
you want more info (and some spoilers), check out this paper by James Grime.