A reel slot machine for playing a bonus game. A player plays a first game on the slot machine according to a first set of odds of winning. If the player wins, the player is given the opportunity to wager the player's winnings on a second “double-up” bonus game. If the user loses the bonus game, the player loses the winnings from the first game. If the player wins the bonus game, the player's winnings are doubled. The player can continue to play the bonus game until the player either loses a bonus game or takes the player's winnings.