Embodiments of the present invention provide methods, systems and programs for conducting game feature. A method comprises: a) upon generation of a game outcome, evaluating the game outcome according to a plurality of evaluation structures against a payout criteria set and a feature criteria set; b) for each evaluation of an evaluation structure that fulfills a payout criterion, calculating a payout value according to a feature attribute associated with said evaluation structure; c) for each evaluation structure having an associated feature attribute and that fulfills a feature criterion, modifying said feature attribute, said modified feature attribute persisting for calculating the payout value of at least one subsequent game outcome; and d) awarding the sum of the calculated payout values of all of the evaluation structures to a player. An embodiment involves a free-spin feature in which the feature attributes are multiplier values evolving and persisting throughout the free-spin feature.