Slot games are incredibly popular and highly entertaining, with action-packed gameplay that makes every spin of the reels a thrilling adventure. There are thousands of games to choose from, each offering unique features designed to maximize the fun factor.
The best online slots keep you engaged with diverse features — custom reel setups, special wild symbols, extra rounds with stacked jackpots, and more — that enhance the experience. If you want to make the most of these game-changing mechanics, keep reading for a guide to slot game design, including some of the more modern additions such as cascading reels, expanding wilds, and pick-and-click mini-games.
How Do Slot Machines Work?
All slots at the best casinos share a few similarities when it comes to the basics. For starters, the base game is essentially a grid filled with reels and rows of symbols. The size and shape of this layout vary from game to game, but it’s always a predetermined set of vertical columns (reels) and horizontal rows.
Reel Types
The number of online slot reels gives a good indication of what to expect in terms of gameplay. Three reels are often the standard setup for classic slots, while larger setups are more common in modern variations. Generally, more reels mean more opportunities for winning combos.
There are also special reels like expanding reels and cascading reels. Expanding reels add rows of symbols that can be unlocked during the base game. Cascading reels, also known as tumbling reels or avalanche reels, replace all winning symbols with new ones, repeating the process until there are no more additional matches.
No matter how big or small the layout is, pressing the Spin button activates the reels. Slots with autoplay settings allow you to play multiple spins in a row, with custom limits that stop the reels when you hit predetermined win/loss thresholds.
Paylines
When the reels spin, random number generation (RNG) ensures that every outcome fills the grid with random symbols. Wins are achieved by landing matching sets of pay symbols. Each game has paylines that award wins based on specific patterns, typically triggered from left to right across the reels.
Different slots have different numbers of paylines. Some online slot paylines offer a few dozen ways to win, while others have thousands of paylines with new and exciting patterns. For example, Megaways games can expand the reels for 117,649 win lines, changing symbol size on every spin to fit up to 49 symbols on six reels.
Multipliers
Like most online casino games, the prize multiplier decides the payout value in slots. Online slot multipliers can be low, high, or anything in between. There are low and high-paying symbols, rising multipliers, and stacking multipliers, and they all increase the size of the win by multiplying the stake per spin.
Gamble Feature
Online slots with a gamble feature up the ante by allowing you to place an additional bet after a win, usually with an even split for winning or losing. The win is doubled if you anticipate the outcome correctly, but you lose everything if you make the wrong choice. Some slots let you gamble with a percentage of the total win instead of risking the full amount.
Slot Symbols
Pay symbols aren’t the only symbols you’ll find in slot games. Many game developers include a mix of wilds, scatters, and symbols to boost the odds of winning. These symbols often unlock the best odds in the game, with generous multipliers that might even lead to a jackpot prize.
Wilds
The slot machine wild symbol, which can be found in most games nowadays, serves the same function as the joker does in popular card games: it substitutes for other symbols in winning combos. Wilds can also transform in different ways, expanding to cover entire reels, turning other symbols into wilds, or becoming sticky symbols on cascading reels.
Scatters
Activate extra features with the scatter symbol in online slots. Unlike regular symbols, scatters can drop anywhere on the reels in no particular order, unlocking mechanics that give you additional spins. Most games require three or more scatters to trigger special features.
Special Symbols
Special symbols are unique to every game where they’re included. In some instances, games add extra symbols with instant cash prizes, while others have mystery symbols that transform into other symbols at the end of a spin. Some of these symbols are tied to game-specific features, like the Link & Win feature found in Microgaming slots, for example.
Extra Rounds
Online slots with extra rounds offer a diverse and delightful assortment of special mechanics and top prizes. These rounds are designed to enhance the experience and increase the chances of winning, and can reward you with anything from extra spins and respins to fixed and progressive jackpots.
Extra Spins
Online slots with extra spins give you additional chances to win without needing to wager again. There are two types found in slot games: extra spins and respins. Extra spins are mostly triggered by scatters, which can either trigger an extra round of regular spins or provide a choice between different spin modes, with special modifiers such as a higher drop rate for the most elusive symbols.
Respins are similar to cascading reels. The symbols that trigger these spins become sticky, and you receive a certain number of spins to create more matches. Additional symbols can reset the respins counter. Typically, extra spins and respins offer the biggest wins in the game.
Jackpots
Fixed and progressive online slot jackpots are the ultimate prizes, but they’re often locked behind mini-games or additional rounds like extra spins. You get pick-and-click options, wheel-based mini-games, and all sorts of other interesting and innovative feature rounds.
Fixed jackpots always pay the same amount when triggered. On the other hand, progressive jackpots take a percentage of each bet and add it to the pot, gradually increasing in size until a lucky player hits the right combo.