Slot features explained

Slot features explained: what counts as a feature?

Every slot starts with the same skeleton: reels, symbols, a way of deciding which combinations pay, and a random number generator picking where the reels stop. A 'feature' is anything that bends those basic rules. Some features act on every spin, such as a wild symbol standing in for others. Others are rare events, such as a bonus round that might land once in a few hundred spins.

It helps to sort them into three groups. Win mechanics decide what counts as a winning combination: paylines, ways to win, cluster pays and pay-anywhere grids. Base-game modifiers act during ordinary spins: wilds, cascades, random multipliers and mystery symbols. Bonus features are separate modes you reach by triggering them: free spins, hold and win respins, pick-me games, wheels and jackpots. The online slots guide explains the basic spin these all build on.

Slot features explained at a glance

We have separate, deeper explainers for several of these, linked in the sections below. The examples are well-known games used to illustrate a mechanic; check any game's own help screen for its exact rules at your casino.

Wilds and scatters: the two symbols behind most slot features

A wild behaves like a joker in cards. It replaces ordinary symbols to complete a win, though most games stop it replacing scatters or bonus symbols. Variations change how long or how widely it acts:

• Expanding wilds stretch to fill a whole reel; see expanding wild.
• Sticky wilds hold their position for a number of spins or for a whole bonus round; see sticky wild.
• Walking wilds move one reel along each spin until they drop off the edge. ELK Studios lists them among its signature mechanics.
• Multiplier wilds carry a factor such as 2x or 3x and apply it to any win they complete.
• Collecting wilds gather the cash values on other symbols. The fisherman in Big Bass Bonanza, which collects fish money values during free spins, is the best-known example.

A scatter is different: it does not need to sit on a payline. Landing three or more anywhere usually triggers a feature, and some scatters also pay a prize on their own, multiplied by the total stake. Book of Dead and its many imitators combine the two roles in one symbol, which is why three books both pay and start the free spins.

Free spins and bonus rounds explained

Free spins rounds are the most common bonus round. You play a set number of spins at the stake that triggered them, and the game usually adds something extra: a multiplier, sticky wilds, an expanding symbol or extra reels. Landing more scatters during the round can award a retrigger, adding spins.

Pick-me bonuses ask you to choose from hidden items, but the result is decided by the random number generator in the same way as a spin; your choice does not change the expected value. Wheel bonuses work similarly. Our guide on how slot bonus rounds work goes through the main types and how triggers are set.

Free spins inside a slot are part of the same game cycle as the spin that triggered them. They are separate from casino 'free spins' offers, which are promotional spins with their own terms; see how free spins work.

Paylines, ways, clusters and pay-anywhere slots

The win mechanic is the rule that decides whether a screen of symbols pays. It is the first thing to understand about any slot, and the most varied.

• Paylines: fixed patterns across the reels, usually paying left to right. Our slot paylines explained guide shows how line bets and total bets relate.
• Ways to win: matching symbols on adjacent reels pay regardless of row, giving 243, 1,024, 4,096 or more combinations.
• Megaways: a Big Time Gaming mechanic, licensed to other studios, where each reel shows a different number of symbols each spin; see Megaways slots.
• Cluster pays: groups of touching symbols pay on a grid. Our cluster pays slots guide covers how clusters are counted.
• Pay anywhere: a set number of matching symbols anywhere on screen pays, as in Sweet Bonanza and Gates of Olympus.

Cascades, multipliers and other base-game modifiers

Modifiers make ordinary spins less predictable. Cascading reels remove winning symbols and drop new ones into the gaps, letting a single stake pay out several times in a row. Slot multipliers scale a win up, sometimes growing with each cascade. A mystery symbol lands as a blank tile and reveals itself as a single matching symbol, while a symbol upgrade turns low-paying symbols into higher ones.

Studios brand their own versions heavily. Nolimit City's xWays, xNudge and xBomb, Avatar UX's PopWins and ELK's CollectR are all named modifiers; the help screen will explain any unfamiliar name in plain terms.

Hold and win respins and jackpot features

In a hold and win round, cash or coin symbols lock in place and you receive a few respins, typically three, which reset whenever a new one lands. Filling the screen often awards the largest fixed prize. Our hold and win slots guide explains the mechanics and the maths.

Jackpots come in two main forms. A fixed jackpot is a set multiple of your stake. A progressive jackpot grows as players stake, sometimes across a jackpot network of many casinos, and part of the game's RTP is set aside to fund it. That is why progressive titles such as Mega Moolah (88.12% published RTP) return less on everyday spins than standard slots.

How slot features affect RTP, volatility and hit rate

A feature never adds money to a game. The developer fixes the overall return first, then decides how to share it between base-game wins and features. A generous bonus round is paid for by leaner ordinary spins.

The splits in that table are illustrative, not published figures for any real game, but they show the trade-off. On a feature-heavy slot with £1 spins, if the bonus lands once every 200 spins on average, you would expect to stake around £200 between triggers, and some gaps will be much longer. That is what higher volatility means in practice. Our slot hit rate guide explains the related idea of how often any win at all appears.

How to read a slot's features before you play

1. Open the slot and find the paytable or help screen (an 'i', menu or book icon).
2. Note the win mechanic: lines, ways, clusters or pay anywhere, and the minimum match.
3. Read what each special symbol does: which symbols the wild replaces, what scatters trigger, and whether any symbol pays on its own.
4. Check the bonus round rules: number of spins, retrigger conditions, multipliers and any maximum win cap.
5. Find the RTP figure and the volatility rating if the studio shows one.
6. Try the game in demo mode if the casino offers it; in Great Britain demo play needs a verified account.

Our guide on reading a slot paytable walks through a real layout section by section.

Slot features you won't find at UK casinos

Several features common in other markets are missing from British slots, mostly because of Gambling Commission game design rules that took effect on 31 October 2021. The Commission's summary of changes to its technical standards (opens in a new tab) sets out the exact wording.

Our page on losses disguised as wins explains the celebration rule, and the questions below cover autoplay and bonus buys. The 2.5-second rule is enforced: in June 2026 Stakelogic agreed to pay £122,835 after some of its slots ran faster than the minimum, as the Commission's Stakelogic announcement (opens in a new tab) explains.

Where to try slots with these features

All three partners below are licensed by the Gambling Commission and carry thousands of games, so you will find most of the features on this page in their lobbies; check the game's help screen for the exact rules. We have not verified each casino's full game list, so search the lobby for any specific title.

PlayOJO (18+, new UK customers excluding Northern Ireland, terms apply) gives 80 free spins at 10p each on Big Bass Bonanza after a first deposit of £10 or more; the game is built around a collect-style free spins round, and spin winnings are paid in cash with no wagering. Coral Casino (18+, new players, terms apply) adds 100 free spins at 10p on selected slots when you deposit with an eligible method and bet £10 on slots; accept them within 48 hours, use them within 7 days, and spin winnings carry no wagering. Casumo (18+, opt-in, terms apply) offers 50% of a first deposit of £20 or more up to £100, wagered 10x within 7 days, with bets capped at £5 while the bonus is live and game restrictions in place.

Features make slots more entertaining, but they do not make winning more likely. Decide your budget before you start, use the casino's deposit limits, and call the National Gambling Helpline run by GamCare (opens in a new tab) on 0808 8020 133, free and open 24/7, if you want support. More explainers are on the guides hub.

18+. Gambling should be entertainment that costs money, not a way to make it. Set a deposit limit before you play: how to set deposit limits. Free, confidential help: National Gambling Helpline 0808 8020 133.