Players take turns saying positive integers less than or equal to 8, but not equal to the number the previous player said, or 9 minus that number, and adding or subtracting that number to a running total. The goal is to be the first player to pass through all ten "hoops" (multiples of 10) up to and including 100. There are two ways to pass through a hoop (a) by saying a number that will reach the opposite side by an equal amount (e.g., if you are at 28, saying 4 will take you through hoop 30 to 32) or (b) by saying a number that lands you in the hoop, and then exiting by the same number on the following turn. If you miss, or are blocked, go back and try again, but you're only allowed to miss the final goal of 100 one time, or else you lose.
One variant allows players an extra move immediately after passing a hoop.