The object of the game is to make the coins on the spinning table either all heads (H) or all tails (T) with as few turns as possible. You decide the version of the game (number of coins) after clicking the green flag. After each spin you can uncover and/or change no more than half of the coins, clicking check to see if you win. If you don't win, then you spin and try again. The coins and their order do not change during a spin, but the spin is a random amount, so you never know where the coins you've just seen will end up.
For the 4 coin version, there is a strategy which guarantees a win in 5 turns or less, no matter how unlucky you get.