A mystery symbol is a blank, question-mark or boxed symbol that lands on the reels and then turns into a regular symbol once the reels stop. In most games every mystery symbol on screen reveals the same randomly chosen symbol, so a cluster of them can become a large group of matching icons at once.
What mystery symbols are
Mystery symbols are a way of creating big blocks of identical symbols without printing them on the reel strip. They often land stacked, filling part or all of a reel. The reveal happens after the spin stops, and the game then pays any wins using the revealed symbol.
The suspense is presentation. The random number generator decides the full outcome, including what the mystery symbols become, at the moment you press spin. The reveal is the game showing you the result in stages.
How it works, step by step
- You place a stake and the reels spin.
- Mystery symbols land in some positions, often in stacks.
- The reels stop and the game reveals the symbol, usually by flipping or opening all mystery symbols together.
- Every mystery symbol becomes that symbol.
- Wins are evaluated across the grid with the revealed symbols in place.
Common variations
- Stacked mystery reels: whole reels of mystery symbols, which can fill several reels with one symbol.
- Wild reveals: the reveal can include a wild.
- Bonus-only mystery symbols: in free spins, mystery symbols may be more frequent, or stay in place.
- Mystery with multipliers: the revealed symbols carry a multiplier.
- Mystery cash: in hold and win and money collect features, mystery coins reveal a cash value or a jackpot.
- Related mechanics: xWays reveals several copies of one symbol in a single position, a similar idea.
What it does to the maths and the feel
Mystery symbols create all-or-nothing moments. A tall stack revealing a low-paying symbol may pay little; the same stack revealing the top symbol can pay many times more. The game's designer weights which symbols can be revealed, and how often, to keep the overall return at the game's RTP. Higher-paying reveals are less likely.
That spread of possible results within a single feature tends to push volatility up. A run of low reveals is not a sign that a high one is coming; each spin is independent.
It also helps to read the info screen before playing. Most games list which symbols a mystery symbol can become, and some show whether wilds or bonus symbols are among them. That tells you what the feature can do, though not how often a particular reveal will happen, which the game does not usually publish.
Rules in Great Britain
Mystery symbol games are available on GB-licensed sites. The usual stake limits and game design rules apply. The reveal sits within the minimum 2.5 second game cycle, and slam stops, which used to cut animations short, are not allowed on GB-licensed online slots.
Questions people ask
Do all mystery symbols reveal the same symbol?
In most games, yes: every mystery symbol on screen turns into the same randomly chosen symbol. Some games reveal different symbols per reel.
Is the reveal decided after the reels stop?
The whole result, including the reveal, is decided by the random number generator when you spin. The reveal animation just shows it.
Can a mystery symbol become a wild?
In some games, yes, and some also include scatters or bonus symbols in the possible reveals. The paytable lists what can appear.