Slot mechanics explained: Megaways, hold and win and cluster pays
Three mechanics power most modern slots. Knowing which one you are playing tells you how a game will pay and how hard it will swing.
Updated · 5 min read
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Modern slots look wildly different from one another, but most of them are built on a handful of mechanics. Once you know which mechanic you are playing, you know a great deal about how the game will feel: how often it pays, how big the swings are and where the real money in the game is hidden.
This guide covers three of the most common designs in a modern lobby: Megaways, hold and win, and cluster pays. It also covers the two numbers that matter more than any theme or animation, RTP and volatility.
First, two numbers: RTP and volatility
Return to player (RTP) is the theoretical percentage of all money staked that a game pays back over a very large number of spins. A 96% RTP slot returns £96 for every £100 staked in the long run, which leaves a 4% house edge. Over a single session it tells you almost nothing about what will happen to you.
Volatility (sometimes called variance) describes how that return is distributed. A low-volatility game pays small amounts often. A high-volatility game pays nothing for long stretches and then occasionally pays a lot. Two slots can share a 96% RTP and still feel completely different.
Many games are released in several RTP versions, and the casino chooses which one to offer. The figure that applies is usually shown in the game's information or paytable screen. It is worth checking, because the gap between a 94% and a 96.5% version of the same game is substantial over time.
Megaways
Megaways is a mechanic created by Big Time Gaming and licensed to many other studios. Instead of a fixed number of paylines, each reel shows a random number of symbols on every spin, typically between two and seven. The number of ways to win is the product of the symbol counts on each reel, so on a six-reel game it changes every spin and can reach 117,649 ways when every reel shows seven symbols.
How wins form
Matching symbols pay when they land on adjacent reels from left to right, in any position. Most Megaways games add cascading (tumbling) reels: winning symbols disappear, new ones drop in and further wins can follow from the same paid spin.
What it feels like
The base game tends to produce frequent small wins, while the serious money sits in free spins rounds with unlimited or rising multipliers. Volatility is generally medium-high to high. The big "ways" number on screen is exciting but is not the same as a high chance of a big win.
Hold and win (respins)
Hold and win games, sometimes branded as "cash collect" or "link" features, centre on a bonus round triggered by landing a set number of special symbols, often coins or orbs carrying cash values. Those symbols lock in place and you receive a small number of respins, usually three. Each new special symbol resets the count. When the respins run out, you collect the values on screen, sometimes with fixed jackpots for particular symbols or for filling the whole grid.
What it feels like
The base game is often quiet, and players spend much of their time waiting for the trigger. The feature is easy to follow and gives a clear sense of progress, which is part of its appeal. Volatility is typically medium to high, with the top prizes reserved for filling the grid, which is rare.
Cluster pays
Cluster pays slots drop paylines altogether. Wins form when a group of identical symbols touch each other horizontally or vertically, commonly five or more. Winning clusters are removed and new symbols cascade in, so one spin can produce a chain of wins. Grids are larger than classic reels, often 6x6, 7x7 or 8x8.
What it feels like
The cascades make spins feel busy and eventful. Many cluster games add symbol upgrades, wilds dropped onto the grid or multipliers that grow with each cascade. Depending on the design, volatility ranges from medium to very high, with games that build multipliers through long cascade chains sitting at the top end.
Side-by-side comparison
| Mechanic | How wins form | Typical volatility | Where the value sits | Common extras |
|---|---|---|---|---|
| Classic paylines | Fixed lines across 3 to 5 reels | Low to high, depends on design | Free spins, expanding symbols | Wilds, scatters, gamble feature |
| Megaways | Adjacent reels, variable symbols per reel, up to 117,649 ways | Medium-high to high | Free spins with growing multipliers | Cascades, extra top reel, bonus buy in some markets |
| Hold and win | Locked cash symbols during a respin feature | Medium to high | Filling the grid, fixed jackpots | Collector symbols, multiplier orbs |
| Cluster pays | Groups of touching identical symbols | Medium to very high | Long cascade chains with multipliers | Symbol upgrades, grid multipliers |
For a sense of the classic end of the spectrum, games such as Book of Dead from Play'n GO use fixed paylines with an expanding symbol in free spins and are well known for high volatility. Studios in the Trixino lobby, including Pragmatic Play, Red Tiger, Push Gaming, Relax Gaming and Yggdrasil, each publish games across several of these mechanics, so it pays to read the info screen rather than assume from the artwork.
Choosing a mechanic for your budget
A sensible rule is to match volatility to the size of your session budget relative to your stake:
- Small budget, many spins wanted: lower-volatility classic or cluster games keep the balance moving with frequent small returns.
- Comfortable with long dry spells: Megaways and high-volatility cluster games are built around rare, large feature wins.
- You like a clear goal: hold and win features show progress on screen, but remember the trigger can take a long time to arrive.
None of these mechanics changes the RTP or makes a game easier to beat. They change how the same expected return is delivered.
UK stake limits on online slots
For operators licensed by the Gambling Commission to serve customers in Great Britain, maximum stakes on online slots were introduced in 2025: £5 per spin for adults aged 25 and over, and £2 per spin for those aged 18 to 24. Features such as autoplay restrictions and minimum spin speeds also apply on GB-licensed sites. These rules apply to GB-licensed operators only, so it is worth knowing which regulator a casino answers to; our guide to checking a casino for yourself explains how.
To see which studios and game types sit in the Trixino lobby, read our overview of games and providers. If you are new to bonuses, our explainer on wagering requirements shows why high-volatility slots and bonus play often mix badly.
Whatever you play, set a budget and a time limit before the first spin, and treat the outcome as the cost of entertainment. Free support is listed on our responsible gambling page.
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