Modern video slots stack a remarkable number of mechanics on top of the basic reel spin. The paytable of a new release can read like a technical specification: expanding wilds, sticky wilds, scatter pays, cascading reels, progressive multipliers, bonus buy. None of it changes the fundamental maths — the house edge is set by the RTP — but understanding the vocabulary makes it far easier to know what you are playing and what the bonus round actually does. This guide covers the features you will meet most often.
Wild symbols
A wild substitutes for other symbols to complete a winning combination, in the same way a joker works in some card games. If a payline shows cherry–cherry–wild, it pays as three cherries. Wilds typically do not substitute for scatter or bonus symbols, and some pay their own prize if enough land in a line.
Wilds come in many forms:
| Wild type | What it does |
| Standard wild | Substitutes for regular symbols on the position it lands |
| Expanding wild | Grows to cover the entire reel it lands on |
| Sticky wild | Stays in place for a set number of spins, usually in free spins |
| Walking/shifting wild | Moves one reel left or right on each spin until it leaves the grid |
| Stacked wild | Appears in vertical blocks, covering multiple positions |
| Random wild | Added to the grid by a random feature after the spin lands |
| Multiplier wild | Substitutes and multiplies any win it contributes to |
Scatter symbols
A scatter pays or triggers a feature regardless of where it lands — it does not need to be on a payline or on consecutive reels. Three or more scatters anywhere on the grid is the most common trigger for a free spins round. Some scatters also award a cash prize proportional to how many appear.
Free spins
A set number of spins played without deducting the stake. Free spins rounds usually come with enhanced rules: extra wilds, larger multipliers, a modified reel set with more high-value symbols, or symbols that become sticky. Many games allow the round to be retriggered by landing further scatters while it is running.
In terms of the maths, free spins are where a large share of a high-volatility slot’s RTP is concentrated. That is why such games feel quiet in the base game — a significant proportion of the return is being “saved” for the feature.
Multipliers
A multiplier increases a win by a stated factor. Multipliers can apply in several ways:
- To a single winning combination (a 3x wild in the line).
- To every win in a free spins round (all wins ×5).
- Progressively, increasing with each consecutive win or cascade (1x, 2x, 3x…).
- Randomly, applied to the total win of a spin after it lands.
Some modern games display multiplier symbols that collect and combine, occasionally producing very large single-spin wins.
Bonus symbols and pick games
A bonus symbol is distinct from a scatter and launches a separate mini-game rather than free spins — often a “pick” screen where you choose from hidden items to reveal cash prizes, multipliers or additional picks. Pick games are usually lower volatility than free spins rounds.
Cascading, tumbling or avalanche reels
After a win, the winning symbols are removed and new symbols fall into the gaps. If the new arrangement forms another win, the process repeats. A single stake can therefore produce a chain of wins. Cascading mechanics are often paired with a multiplier that increases with each consecutive cascade.
Respins
A respin spins one or more reels again while holding the others. Some games award respins when specific symbols land; others let you pay for a respin on a chosen reel.
Bonus buy
Some slots allow you to pay a fixed multiple of your stake — commonly 50× to 200× — to enter the bonus round immediately, skipping the base game. Two points to note. First, the RTP of a bonus buy can differ from the base game’s RTP; some are higher, some lower, and the figure should be shown in the game information. Second, buying the feature dramatically increases the amount staked per “event”, which is why some regulators restrict it. In Great Britain, bonus buy features are currently not permitted on slots offered to UK customers.
Gamble features
After a win, some games offer a double-or-nothing gamble — guessing a card colour, for example. These typically have zero house edge on the gamble itself but increase variance sharply. They are also uncommon in the UK market now due to regulatory changes.
Reading a paytable
| Section | What to look for |
| Symbol values | Payout for 3, 4, 5 of each symbol at your stake |
| Special symbols | Which are wild, which are scatter, what they do |
| Feature rules | How free spins trigger, how many, what changes inside |
| Multiplier rules | Where they apply and whether they reset |
| RTP and volatility | Usually at the end of the information screen |
| Max win | The cap on any single spin, expressed as × stake |
Features add variety and are the main reason different slots feel different. They do not add expectation. A game with twelve features and 94% RTP returns less over time than a plain three-reel game at 97%.
Related reading on site: Slot Guide; “How to Get Started with Online Slots”.
Features add variety, not an advantage. The house edge applies whichever feature is active.
