A gaming system including a cascading symbol or tumbling reel game which utilizes zero, one or more upgrades in association with zero, one or more shifting symbols. Upon an occurrence of an upgrade event, the gaming system upgrades one or more aspects or attributes of one or more games played. In certain embodiments, such upgrades pertain to upgrading one or more symbols displayed at one or more symbol display positions of one or more symbol display position grids. In certain other embodiments, such upgrades pertain to upgrading the award evaluation of one or more symbols displayed at one or more symbol display positions of one or more symbol display position grids. In certain other embodiments, such upgrades pertain to upgrading one or more attributes or features of one or more bonus or secondary games which are subsequently triggered.