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Expanding symbols are a common feature in many online slot games, particularly modern video Slots, and they’re often found in some of the best online games available. This mechanic changes how symbols behave once they land on the reels, often covering more space than a standard symbol would. The visual effect is noticeable, and expanding symbols play a practical role in how symbol combinations might form during a game round.
You’ll find expanding symbols across many licensed online slot titles, where they’re used to add variety to standard reel behaviour without changing the core structure of the game. Here’s how this feature works and what happens on the reels when it appears.
What is an expanding symbol?
An expanding symbol is a special symbol that grows to fill extra positions on the reel – or sometimes across multiple reels – after landing. Instead of occupying a single space, it may stretch vertically to cover an entire reel, or horizontally across neighbouring reels, depending on the game’s design.
This expansion usually happens immediately after the reels stop spinning and before symbol combinations are checked. The expanded symbol is treated as occupying all the positions it covers for that round.
How expanding symbols are triggered
Expanding symbols can appear in several ways:
- Randomly during base gameplay
- Triggered by landing a specific symbol
- Activated as part of a bonus round
- Linked to free spins or feature rounds
In some Slots, only certain symbols can expand, such as wilds or themed high-value symbols. In others, the expanding symbol is selected at random from the reel set once a triggering condition is met.
The rules for triggering this feature are always defined in the game’s help or information section.
Types of expanding symbols
There isn’t just one type. Developers use several variations, including:
- Expanding wilds: These are among the most common. When a wild expands, it usually fills the entire reel, substituting for other symbols wherever it appears.
- Expanding regular symbols: In some games, standard symbols expand instead of wilds. These often relate to the game’s theme and may be tied to specific features or bonus rounds.
- Partial expansions: Not all expanding symbols fill an entire reel. Some expand to cover only a section, such as three positions in the centre of the reel.
- Directional expansions: Certain symbols expand only upwards, downwards, or sideways, rather than filling all available positions.
Each variation affects symbol matching in a slightly different way, depending on the reel layout and paylines or ways-to-play system.
Expanding symbols and pay systems
How expanding symbols interact with potential payouts depends on the slot’s pay system. In fixed payline Slots, expanded symbols may help complete a line by covering multiple positions along that path. In “ways to play” games, expanded symbols could increase the number of matching combinations across neighbouring reels.
In grid-based or cluster-style Slots, expanding symbols may help form larger symbol groups, which are then checked according to the game’s cluster rules.
Regardless of the format, expanding symbols don’t change how outcomes are generated. The Random Number Generator (RNG) determines symbol placement first, and the expansion is applied afterwards according to set rules.
Are expanding symbols always active?
Not always. In some games, expanding symbols only appear during specific features, such as free spins. In others, they may be part of the base game but triggered less often. Some Slots also include multiple expansion mechanics that activate under different conditions.
Because of this, two games using expanding symbols can behave very differently, even if the feature name is the same.
