In a first aspect, the invention provides a game server configured to communicate during use with at least one player terminal, each of which is configured to facilitate play of a centrally drawn game, the game server configured to: determine that a win rule of the centrally drawn game has been satisfied; determine a prize corresponding to satisfaction of the win rule; and find a probabilistic game instance having a prize outcome corresponding to the prize, at least in part, by executing one or more probabilistic game instances to attempt to find a probabilistic game instance having a prize outcome corresponding to the prize.