A gaming machine for conducting a wagering game includes at least one display and a controller coupled to the display. The display is adapted to display a randomly selected outcome of a basic game of the wagering game. The display displays at least one free spin of a plurality of reels to indicate a free-spin outcome in response to satisfaction of a free-spin event condition in the basic game. At least one possible free-spin outcome is a special-event outcome for permitting play of the special-event. The special-event includes a plurality of levels. Each level has player-selectable elements masking awards including a level-advance outcome. The level-advance outcome allows the player to advance to a next level in the special-event.