In this Game one side bets his/her Marbles against the other. The other side guesses if the amount is even or odd. Depending on if the guess was right or wrong, he/she loses or wins the amount of marbles that were bet by the other side. Then the roles swap in the following turn. Both of you alternate between these turns until one wins all the Marbles and the game ends.
So without further ado. Enjoy!