Slot bonus features are the special mechanics that sit on top of a game’s basic reels and paytable, such as free spins, multipliers, special wilds, respins, hold and win rounds, pick bonuses, wheels and cascading reels. They are paid for out of the game’s RTP, so they change how a game feels and how its returns are spread, not how much it returns overall.
This guide is an overview. Each feature has its own page with more detail, linked below.
How features fit into the maths
Every slot’s RTP is shared between the base game and its features. If a free spins round accounts for a large share of the return, the base game has to pay less to compensate. That is why base-game spins on feature-heavy games often feel thin.
It is also why features drive volatility. The bigger and rarer a feature’s potential, the more the game’s return is concentrated in moments most sessions never see.
Free spins
The most common feature. Land a set number of scatter or bonus symbols and you receive a batch of spins at no extra cost, played at the stake that triggered them. Something is usually different during free spins: extra wilds, rising multipliers, special symbols or a modified reel set. Many games allow retriggers.
Multipliers
Multipliers multiply a win by a set amount. They can attach to a wild, a symbol, a cell on a grid or the whole spin, and in many games they rise with each cascade or free spin. Multipliers are a major source of very large outcomes.
Wilds
A wild substitutes for other symbols to complete a win. Variations change how it behaves:
| Feature | What it does |
|---|---|
| Expanding wilds | Grow to fill the whole reel |
| Sticky wilds | Stay in place for several spins |
| Walking wilds | Move one position each spin until they leave the grid |
Wilds can also carry multipliers or be added to the reels during features.
Respins
Respins re-spin some reels while others stay locked, usually after a near-complete combination or a special symbol. Respins are the building block of several other features, including hold and win.
Hold and win
In hold and win games, landing a set number of special symbols, often coins carrying cash values, triggers a round of respins. The special symbols lock in place, and each new one resets the respin counter. The round ends when you run out of respins or fill the grid, which often pays a top prize. Money collect mechanics work in a similar spirit, with a collector symbol gathering values shown on other symbols.
Pick bonuses
A pick bonus asks you to choose from hidden items, such as chests or cards, to reveal prizes. The choice is presentation: the outcome is decided by the RNG, and the items are not a test of skill or intuition. Some studios reveal the unpicked items afterwards, which makes it feel as though a different choice would have won more. It would not have; the result was already set.
Wheel bonuses
A wheel bonus spins a prize wheel whose segments might hold cash prizes, multipliers, extra free spins or jackpot tiers. As with pick games, the result is decided by the RNG, and the segments you see are not necessarily equally likely.
Cascading reels
With cascading reels, winning symbols are removed and new ones drop in from above, which can form further wins in the same spin. Cascades are central to cluster pays and Megaways games and are often paired with a multiplier that grows with each cascade.
Other features you will meet
- Mystery symbols: land as a blank and all turn into the same randomly chosen symbol.
- Symbol upgrades: low-paying symbols are swapped for higher-paying ones, often during free spins.
- Split symbols: one position counts as two or more symbols.
- Grid expansion: extra rows or reels unlock as the feature progresses.
- Nudges and holds: the classic UK fruit machine features.
- Gamble feature: an option to risk a win on a card colour or ladder for a chance to increase it. Even at fair odds it adds risk, not value, and the rules screen says how it is priced.
Bonus buy (not on GB sites)
Bonus buy lets players pay a lump sum, often a large multiple of the stake, to go straight into a feature. On 17 January 2020 the Gambling Commission told licensees that bonus buys break its Remote Technical Standards, and they are not offered on GB-licensed sites. You will still see it in reviews and videos aimed at other markets.
Features and the GB design rules
Since 31 October 2021, GB online slots must not use sounds or imagery to celebrate a return that is equal to or less than the stake. That applies to features too: a free spins round that pays back less than the stake should not be presented as a win. The game design rules page lists the other requirements, such as the 2.5 second minimum spin time.
Reading feature rules
Every feature has rules in the game’s information screen: how it triggers, how many spins or picks it gives, whether it can retrigger and whether it has a cap. Read them before you play, as covered in how to read a paytable. If you want to see a feature in action without staking, demo modes on GB sites are available once your age and identity are verified; see free slots and demo play.
The short version
- Features are paid for from the game’s RTP, not on top of it.
- Free spins are triggered by scatters and played at the triggering stake.
- Multipliers, special wilds and cascades create the biggest outcomes.
- Hold and win locks cash symbols and resets respins with each new one.
- Pick and wheel bonuses are decided by the RNG; your choices are presentation.
- Bonus buy is not offered on GB-licensed sites.
Questions people ask
Do bonus features increase my chances of winning?
Features are part of the game's RTP, not an addition to it. A game with frequent or generous features pays less in its base game to compensate, so the overall return is the same as the stated RTP.
Can I buy a bonus feature on GB sites?
No. Bonus buy is not offered on GB-licensed sites. In January 2020 the Gambling Commission told licensees that feature buys breach its technical standards.
Are free spins in a slot really free?
Free spins triggered inside a game cost nothing extra, because they are paid for by the stakes that went before. They are played at the stake that triggered them and form part of the game's RTP.
What is the difference between a bonus round and a feature?
The terms are used loosely. A feature is any special mechanic, and a bonus round usually means a separate stage of the game, such as free spins, a pick game or a wheel, triggered by special symbols.
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