Online video slots have evolved from simple lever-pulled machines into immersive games featuring multiple paylines, advanced reel mechanics, wild symbols, scatter symbols, jackpots, and engaging bonus rounds. This guide explains how modern video slots work, covering paylines, features, mechanics, RTP, and volatility, giving you everything needed to understand and enjoy slot gameplay.
Table of Contents
History of Online Slots
The slot machine has come a long way since an American, Charles Fey, invented the first one back in the 1890s. A mechanical machine, playing involved pulling a lever to determine when the reels would stop. Using symbols we still see today, such as fruits, bells, bars, and horseshoes, the slot machine quickly became popular in saloons all across America.
The premise of slot machines is still closely related to those early renditions; you put your money in and hope you get lucky enough to match up some symbols across the paylines.
Of course, over the years, slots evolved, developed and became better. One-armed bandits featured prominently in land-based casinos for decades (and still do).
Then came the first video slot, which was developed in 1976 by Fortune Coin Co. This was called Fortune Coin and was the first slot machine that was no longer mechanical. It featured a 19″ screen, and the results were determined by a logic board. This slot became hugely popular and was the pioneer of the many physical and online video slots we see today. Two years after releasing that title, Fortune Coin Co. was acquired by IGT (heard of them?).
It was not until the mid-1990s that video slots started to become mainstream.
The internet allowed top casinos to come to us rather than the other way round. From the very start, video slots were the most popular casino game at online casinos, and today we have thousands of them to choose from. They feature cutting-edge graphics and animations, innovative reel mechanics, and exciting bonus features.
In this guide, I will break down the different aspects of a video slot. I will explain the stakes offered, the bonus features you can enjoy, the reel mechanics used to elevate gameplay and determine how you’re paid, and the innovative bonus features that add to the gameplay experience!
Random Fact
Did you know that video poker was invented before the slot machine? Sittman and Pitt Company created machines that had 5 reels with 10 playing cards on each. As you know, that means 50 cards when a standard deck has 52. Well, to increase the house edge and allow saloon owners of the time to pay out fewer prizes, two cards were removed from the full deck of cards: the 10 of spades and the jack of hearts. The idea was to create a minimum poker hand to win some prizes. At the time, prizes often involved beer, whiskey, or cigars.
Technically, these games operated in the same way as slots. You put your coin in, and the reels/drums would spin until you pulled a lever. At this point, the reels stopped to reveal your hand.
A Look at How Reel Mechanics Have Evolved
Over the years, slots have evolved due to advancements in technology and software. While classic slots offered simple reel mechanics, new mechanics are coming out all the time that add to the gameplay. Rather than matching symbols across a payline or two, new slots often look like mobile puzzle games and give you so many different ways to win. We have listed four of the most common, but you’ll find others, such as Infinity Reels and Hold & Win, when playing some slots.
Paylines (Since 1890s)
This is the classic reel mechanic that even the first slot machines used. These are lines that you need to form matching combinations on. Usually, you need to land at least 2/3 matching symbols starting on the first reel and moving right along the payline. Some slots also utilise pay both ways mechanics, which means you can land winning combinations from right to left or left to right. Older slots usually have a small number of paylines, such as 1 or 3, but over the years, slots have developed to have as many as 50 paylines.
Payline Slot Machine Guide: Discover demo slots and pokie games that utilize paylines and learn how this reel mechanic works via our Payline Slot Machines guide.
Ways to Win
One of the best new reel mechanics is Ways to Win, which was developed by Microgaming. When spinning the reels, this feels similar to a standard payline slot, but it actually offers so many more paylines. As long as you have matching symbols anywhere on consecutive reels, they will contribute to wins. Again, you normally need a minimum of 2 or 3 matching symbols, but they can be on any position on each reel rather than on active paylines. First, there were 243 ways-to-win slots, then 720 ways-to-win, and now you can find slots with ways to win into the thousands! The ways to win can increase depending on how many reels and rows there are.
Cluster Pays (2016)
I mentioned that some games look and feel like mobile puzzle games, and most of these will be cluster pay slots. This is a reel mechanism that NetEnt developed a few years back. Like puzzle games, you match symbols in clusters rather than on paylines. Often incorporated alongside cascading/tumbling symbols. This means you do not have to worry about starting your wins on the first reel.
The clusters will pay regardless of their location. Clusters are matching symbols that are connected vertically or horizontally. This mechanic is often accompanied by the cascading/tumble symbols feature, too. This removes winning symbols and allows other symbols to tumble into their place. When this happens, there is a chance to win sequential wins from a single spin. A good slot that uses this mechanic is Aloha! Cluster Pays by NetEnt.
Megaways (2015)
Developed by Big Time Gaming, this is one of the most popular reel mechanics, which came around when the software provider released its Dragon Born slot game. Slots and pokies that use this reel mechanic can have anywhere between 64 ways to win (2 symbols per reel) and 117,649 ways to win (7 symbols per reel).
- Big Time Gaming has trademarked this mechanic but licenses it to other slot developers, which is why you will find numerous Megaways titles at the casino.
- Each spin produces between 2 and 7 symbols per reel on a 6-reel online slot/pokie game. This works by randomising how many symbols are on each reel for each spin. You could have 2 symbols on the first reel, 5 on the next, 7 on the next, and so on.
- The more symbols on each reel, the more ways to win there. As per the example above, 7 symbols on every reel will give you the maximum number of ways to win on a given spin, while 2 symbols on each reel will give you the least number of ways to win.
TrueWays (2022)
BGaming released the first online slot to use TRUEWAYS™ in 2022. The Truewyas reel mechanic uses 2 to 8 symbols per reel at random, which can result in up to 262,144 ways to win. The reels work similarly to Megaways, except each spin can produce between 2 and 7 symbols on a Megaways slot game, while TrueWays reels can produce up to 8 symbols per reel. Currently, only BGaming owns this slot mechanic, which is available to players who play at online casinos under the Malta Gaming Authority, Curacao GCB, Anjouan licensing authority and the Kahnawake Gaming Commission (KGC).
Full reel mechanics guide: Learn about the different ways online slots and pokies payout symbols combination win via our full guide covering
Types of Slot Machine Reel Mechanics Explained.
Popular Slot Bonus Features
Another area of video slots that has evolved over the years is the range of bonus features they can offer. The very first slots had none at all, but over the years, we saw things such as gamble features (where you can gamble a combination win to double it) and wild symbols (act like the joker card in a pack of cards and can become any symbol needed). As there are so many, we will not list them all. Instead, we will take you through some of the most common bonus features that you will find when playing slots.
Wild Symbols
A standard wild symbol is able to substitute for any other symbol when it can help to create a winning combination. However, even this classic bonus feature has evolved over the years. You can now find expanding symbols that expand to fill an entire reel, roaming wilds that can move from reel to reel during spins, and colossal wilds that are wild symbols that take up positions across several reels.
Scatter Symbols
If they have a payout value, scatter symbols do not have to land on specific paylines to reward that payout. As long as you land the minimum required, anywhere in view, you will earn the reward. These symbols are also used to trigger other bonus features such as free spins or bonus rounds. Normally you need to land 3 or more scatter symbols to trigger the features.
Free Spins/Respins
Free spins are exactly that, spins that are free. Usually triggered by scatter symbols, a free spins round is a batch of reel spins that do not cost you any money. Depending on the slot, you could get, 5, 10, 15, 20, or even as many as 50. You do not pay to spin the reels and could land payouts for free. Repins are similar but normally work by spinning selected reels for free rather than all of them.
Multipliers
This is a simple feature that just multiplies the original payout of a symbol combination. Multipliers can be attached to wild symbols, so that any winning combination completed using a wild symbol will bring a 2x, 3x, 5x, etc, multiplier of that symbols payout. Free spins can also have a multiplier attached, while some slots will allow you to collect symbols to increase a multiplier.
Jackpots
All video slots will have a jackpot of some kind. It could be a local jackpot won by hitting a particular symbol combination or a progressive jackpot that increases over time as you spin the reels. Some video slots even have a progressive jackpot that grows over a shared network. So all players using those slots contribute. On WowPot or Mega Moolah (Microgaming) slots, these jackpots can payout millions!
Bonus Games
Usually triggered by scatter symbols, you can also play bonus games on some video slots. They could be picking games where you select symbols to reveal a random cash prize/multiplier. It could also be something unique to the game such as a fighting sequence whereby you choose a fighter, and if he wins, you earn a prize. You will see so many different types of bonus games when playing different slots.
Online Slots in Perspective
Online video slots are more than just spinning reels — they blend paylines, mechanics, and bonus features into engaging games for every type of player.
By understanding RTP, volatility, and features, you’ll be better equipped to choose the right slots, enjoy the gameplay, and maximize your entertainment.
Want to explore without risk? Try free slot demos first to test features and mechanics before playing for real money.
FAQ
What is RTP?
RTP is the return-to-player percentage that every online slot, and indeed casino game, has. This is a percentage of money received that a slot will pay out over an extended period of time. So, a slot with a 96% RTP (which is about the average for video slots) will pay out $96 out of every $100 earned. However, it does not mean that you will receive 96% of your wager. Every spin is independent of the others and random. It is the percentage that the game will payout from the money earned from all players. So, you could lose your entire $100, while another player doubles his $100 to $200 – essentially getting your share.
What is Variance?
Variance (or volatility) is the manner in which an online video slot payout occurs. It determines the average regularity and sizing of payouts a slot makes. A low volatility slot will pay out often, but usually in small amounts. A high variance slot does the opposite, so it pays out rarely, but in much bigger amounts. A medium variance slot falls somewhere in the middle of the two. The variance has no effect on the RTP of a slot; it just determines how the slot pays out that return to player percentage.
What is the Min/Max Bets Allowed on Video Slots?
This depends on the particular slot. You can find penny slots that let you bet as low as $0.01 while others may have a minimum bet of $0.10 or $0.20. As for the max bets, this also depends, as some might let you bet no more than $10 per spin, while others could let you wager as much as a couple of hundred on each spin. This means that there are slots at reputable online casinos that will match the budgets of everybody. Obviously, if you have a small bankroll, you will want a slot that allows a lower minimum bet, while high rollers will want to play on slots that accept larger wagers.
Where Can I find the Winning Combination/Payouts on a Slot?
All slots will have a paytable somewhere that explains how the slot payouts work and what each payout is for each particular winning combination. On older classic slots, this was actually on the main screen to the left or right of the reels. However, modern slots fill the entire screen, so the paytable is often moved elsewhere. You normally have to click into a menu or an ‘i’ icon to find it.
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