TOWER STACK™ FEATURE PANDA: Stands tall in a new stack series with 16 vertical reel positions and 4 progressive levels. Players can select to play up to 3 frames totaling 150 paylines. Playing the PLUS FACTOR ante bet adds an extra selectable play area according to reel angle, increases the number of wild on reel 5 and enables the jackpot challenge feature containing bonus credit prizes and 4 progressive levels. Up to 500 free games are awarded by the free games number drawing when the free games are first triggered.