A Mystery Symbol is a surprise feature where symbols appear on the reels with their identities hidden, and after the spin stops, all mystery symbols on the screen simultaneously transform into one single, identical symbol. The core of this feature is to provide players with dramatic tension and anticipation of "what symbol will it be?" until the moment the result is revealed, and the thrill of a reversal where, depending on the outcome, an ordinary spin can be turned into a moment of huge payouts.