Expanding Symbols

Slot Mechanic

Expanding Symbols

Slot Mechanic

Expanding Symbols on Slots

Expanding Symbols: a Game-Changing Mechanic?


Online slot games have come a long way since their humble beginnings, constantly evolving to provide players with exciting and innovative features. One mechanic that has captured the attention of many players is the concept of expanding symbols. This article will delve into the ins and outs of expanding symbols in online slots, take a look at their pros and cons, and provide examples of games that use this mechanic.

Understanding Expanding Symbols

Expanding symbols are a development in slot games where specific symbols have the ability to expand and cover multiple positions on the reels, in some case covering the entire reel. When triggered, these symbols can increase you chances of landing winning combinations to unlock rewards.

How Expanding Symbols Work

Typically, expanding symbols are activated by specific triggers such as landing a particular symbol combination or a bonus symbol. Once activated, the symbol expands vertically (usually) or horizontally and may fill an entire reel, increasing the potential for creating wins. Expanding symbols often come with additional features like wild substitutions, multiplier boosts, or re-spins, building the excitement and potential pay out.

Development and Pioneering Companies

starburst slotThe concept of expanding symbols was first introduced by the Swedish gaming software provider, NetEnt, with their ground-breaking slot game “Starburst” in 2013. Starburst Wilds (the colourful star symbol) can land on any of the three middle reels, and they will expand to cover the entire reel and remain anchored in place for up to three re-spins.

The expanding wild feature is fun, and can give you some decent wins. It’s the secret to the success of this game, and this feature has been copied many times over by other games developers, and NetEnt have used it on many other games such as Gonzo’s Gold, the sequel to their first explorer Avalanche Wins slot: Gonzo’s Quest.

Pros of Expanding Symbols

Increased Winning Potential
Expanding symbols boost the chances of forming winning combinations. With an expanded symbol occupying multiple positions, the likelihood of aligning identical symbols on active pay-lines is enhanced.

Enhanced Visual Appeal
The visual impact of expanding symbols is a real draw. Watching a symbol expand and cover the entire reel creates a sense of anticipation and excitement, adding an layer of immersion to the gameplay.

Intensified Bonus Features
Expanding symbols often come with bonus rounds, free spins, and other exciting features. These symbols can trigger additional rewards such as re-spins (eg Starburst), multipliers, or stacked wilds, boosting the gameplay which can lead to higher payouts.

Cons of Expanding Symbols

Volatility and Balance
While expanding symbols offer the potential for decent wins, they can sometimes result in higher volatility. Players may experience periods of gameplay without much action, which can be frustrating.

Limited Symbol Selection
Expanding symbols typically focus on a few select symbols in the game, which may limit the variety and creativity of winning combinations. This can lead to predictability in the game. You might tire quickly of this mechanic if it is offered in isolation.

Notable Games Featuring Expanding Symbols

book of dead slot gameBook of Dead: This Egyptian-themed slot game from Play ‘n GO is probably their most famous game. You’ll see Expanded Symbols in the free spins bonus

Book of Oz (Triple Edge): Just like other “Book Slots”, one symbol is chosen randomly to function as the expanding symbol in the free spins feature. It will then cover one or more reels, and will boost your winning chances.


Expanding symbols are a popular feature in the world of online slot games, providing players with an immersive experience with the potential for decent wins. The concept continues to evolve: they undoubtedly bring an added layer of excitement and anticipation to games.