One aspect of the disclosure relates to providing durational promotions to players in an online game. The system may adjust the outcome probabilities of winning in a slot machine type of game once the player's content drops below a predetermined threshold so that the player will experience some substantial winning in the initial period. The system may adjust the outcome probabilities of winning in the slot machine type of game for a period of time once a player has purchased content to continue to play the game. This may temporarily adjusting outcome probabilities within the game in favor of a player that has recently made a purchase. This may facilitate positive player experiences subsequent to making purchases, thereby increasing further purchases and/or the likelihood thereof.