What Are the Differences Between the Various Types of Slot Machine?

We take a look at many of the most popular types of game labelled as “slots” by online casinos.

Slot machines have come a long way since first being invented in the late 19th century. Their inventor was a man named Charles August Fey, who was a Bavarian-born American that worked as a mechanic in San Francisco around that time. Fey’s first design called the Liberty Bell was heavily influenced by the poker machines which had appeared just a few years earlier in 1887.

Those earlier machines couldn’t be called slots in the modern sense because they didn’t even accept or pay out money without the assistance of a human operator. Historically speaking though, there is no doubt that both early types of gambling machine are undeniably related. Interestingly, whilst both the poker machine and its more technically advanced cousin were both American inventions, the term “Pokies” is still used to refer to all types of slot machine in Australia.

Gaming machines were very popular from the moment they were devised, becoming an instant hit in the casinos and bars of San Francisco. As the Industrial Revolution began taking hold at the beginning of the 20th century, symbols of fruit had become the most popular design for the reels of slot machines, earning them the nickname of “Fruit Machines” by 1907. The legendary “BAR” emblem also sprung up around this time, although it isn’t clear if Herbert Mills’ “Operator Bell” was the true birthplace of this symbol or if he simply copied it from elsewhere.

The Introduction of the Video Slot

It would be another seventy years or so before the first video slot appeared in 1976, but anyone who has visited a land-based casino recently can tell you it didn’t take long for this newer type of machine to replace its electromechanical predecessor.

Today, actual reel strips are very rarely found in new games being designed for the casino floor. The handle, previously ubiquitous as the primary method of setting the reels in motion, has now been relegated to a backup option – if one is present at all.

Modern slot machines have simple buttons or touch screen icons to start play, which allows the player to remain comfortable in their seat whilst playing these machines for extended periods. This made these games ideal for being converted into online games when the internet began reaching hysteria-level popularity around the turn of the millennium.

There are now many types of game which come under the “slots” umbrella, so what are the differences between all of them? Whilst some online casinos just throw these games together in one section of the casino, other sites might help you out by dividing them into genres such as 3-Reel and 5-Reel Slots, 3D Slots, Grid Slots, Fruit Machines and more. We’re going to take a look at all the most popular and common types below – which are your favourite?

Classic Slots

You’ll sometimes find these games advertised as “Basic Slots” or “3-Reel Slots”, but the three different terms are usually completely interchangeable. Many of the earliest video slots were digital recreations of early three-reel games, though it wasn’t long before the designers of those machines realized they could do so much more as they were no longer constrained by physical reel strips.

Online casinos still wanted to have some of these classic designs among their selection of slot machines, as they do often play very differently – and so can attract a very different type of player – compared to their more modern counterparts.

Whilst some video slots might require several hours of play before you have seen everything a particular game has to offer the majority of classic slots tend to be a much more constrained experience. For some that makes these games monotonous and dull, whereas other players enjoy the relative simplicity of the older three-reel style. This has even led to the appearance of a handful of modern machines which have buttons and note/ticket input and output hardware alongside physical reel strips, such as the Double Diamond series of classic slots that can be found all over Las Vegas.

The majority of classic slots have all of their RTP tied up in the various permutations of symbols which can be achieved through by spinning the reels in regular gameplay. Whilst many video slots players will bemoan the lack of a bonus round or free spins feature, for some this can be a refreshing change to spending the majority of their session just waiting for the scatter symbols to finally drop and award some elusive free spins.

There are a few classic slots with bonus features, but they are few and far between. A common feature of these games is that you will often be required to play “max bet” to be eligible to win the true jackpot. This can be quickly discerned from a brief inspection of the paytable and whenever such a rule is included you should ALWAYS ensure you are betting the maximum number of coins. If you do not, the games RTP could drop by as much as 20-30%! This applies to classic slots found at online casinos too, so make sure you don’t fall into this trap.

Fruit Machines

If you read the introduction but are yet to spend much time playing any of these games, you could be forgiven for expecting modern-day slots and fruit machines to be one and the same. Fruit machines sometimes have skill-based features such as the option to “hold” or “nudge” the reels after each spin. Choosing whether to utilize this facility and understanding the reasons for doing so are essential requirements for a winning fruit machine player.

Slot machines require no such knowledge of skill-based elements, instead relying entirely on their random number generator to decide what the outcome of each spin or session will be. On the other hand, fruit machine players will quickly find that their session is sure to be a loser without making use of these features. For example, when two matching symbols appear on the reels it is a good idea to hold them in place during the next spin. This is because doing so can increase your chances of hitting a matching symbol the next time the third reel spins.

Additionally, fruit machines pay out in a very different way to a slot machine too. A fruit machine will usually only pay out a jackpot if it has enough money inside it to do so. The outcome of each spin is not completely random, instead being influenced by how many wagers have already been placed on the machine that day. A certain percentage of the money put into the machine is retained as profit for its owner, and this will usually be a larger number compared with the house edge of a typical video slot.

Fruit machines can be found online too, and this is arguably a much fairer setting for them – you have no idea who has played such a game before you, so you have no way of knowing if it is “due” to pay out or not. When playing fruit machines in a pub or a bar you always want to jump on a fruit machine after another player has lost plenty of money before ceasing play. If you do play fruit machines in a real-life setting, then be aware of this fact, but also keep in mind that not all operators will empty these machines daily. There is always a chance that the machine is already heavily stocked with cash, even if you seem to be the first person to play that day.

Video Slots

Most online slots fall into this category, though some casinos will bundle ALL of their slot machines – even if they are fruit machines or classic slots – under this one heading, which could be confusing to some players. There are thousands of video slots available online, with individual casinos sometimes offering as many as 3,000 different games of this type. There are often many exclusive games too – whether that be online exclusives that cannot be found in land-based venues, or vice-versa.

Even land-based casinos will usually have a couple of hundred video slots on their floor as a minimum, as they tend to bring in a far greater share of profits compared with table games such as roulette or blackjack. That’s because video slots are incredibly popular with most gamblers in all corners of the globe, although US players seem particularly keen on them. Gamblers spend hundreds of millions of dollars playing slot machines annually in both Las Vegas and Atlantic City, a fact that has probably contributed to the slow rollout of online gambling in the US.

Whilst the first video slots were basic and did little more than attempt to copy the gameplay of classic slots, they soon evolved and began featuring impressive graphics, animation and sound. Developers were quick to realize that they could use any theme they liked, too, leading to a deluge of video slots featuring licensed properties such as movie characters, sports teams, pop stars and the like.

Video slots can be further broken down into many smaller categories, and some would argue that many of the other types of game mentioned below are actually just video slots with slightly different rules or mechanics. This may be true, but as with different types of music or film, it is often helpful to divide a category as broad as video slots into many subgenres. This makes it easier for fans of a certain type of game to search for other similar games, or to stay away from machines they know they will not be interested in.

Video slots are usually labelled with a number known as a Return to Player percentage or RTP, which is another way of specifying the house edge of a casino game. The majority of online video slots have an RTP somewhere in the range of 92-98%, with the remaining number between this and 100 being the house edge of that particular game. For example, a video slot with an RTP of 98%, therefore has a house edge of 2%.

Playing a game with a lower house edge is always advisable compared to a higher one. There are other things worth considering other than RTP when deciding which game to play though, so be sure to read our article “Loose Slot Machines and the Meaning of High and Low Variance Slot Games” for a more detailed look at the differences between the various kinds of video slot.

3D Slots

This is a great example of a type of slot machine that is just a slight evolution on a typical video slot, so it seemed like a good one to mention immediately after video slots. Just like a video slot, a 3D slot can feature several bonus features or none, it might feature a free spins mode or Pick-Me feature, and it may have five, six or even seven reels with who knows how many pay lines or pay ways laid out across them.

Betsoft were the first developer to coin the term 3D slots when they began to use advanced graphics to make their video slots stand out from the rapidly growing market of online gaming companies. Many times, 3D slots will attempt to add a little more narrative and storyline to the slots experience. Virtual characters will often be used for this, along with real voice acting and 3D animations.

Some players will no doubt find these attempts at making slots more immersive and narrative-driven interesting and attractive. Others will ask “why?” and search for the pay table and RTP – things that REALLY matter to players of video slots. It’s easy to imagine younger players being interested in these games – those who grew up on PlayStation probably expect nothing less than 3D graphics and real voice acting, after all. On the whole, whilst 3D Slots might not be much different to a regular video slot, I think it is fair to say they have their place in the market.

Megaways Slots

The term “Megaways” refers to a specific reel layout that was first used by Big Time Gaming (BTG) in their game Dragon Born which was released in 2015. That slot didn’t really take off after its release and remains relatively unknown among the majority of online slots players. You might well have heard of its follow-up though… the infamous Bonanza, which was a smash hit which is still being played heavily today.

Megaways games feature six reels, but the size of the individual symbols on the reel strips is not fixed and can vary in height such that you have anywhere between two and nine different symbols on each of the six reels after every individual spin. The result is that the slot ends up having a completely random number of pay ways every time you press the spin button, up to a maximum of 117,649.

Wins will usually explode and cascade after each spin, and increasing multipliers are regularly used in the bonus features of Megaways slots. These things combined give the possibility of an enormous win, and the result of that has been a huge number of truly amazing hits being shown off by players of these games during the last five years.

In a very unusual turn of events, Bonanza was so popular that BTG could license the Megaways concept to other slot developers who wanted to build their own games which utilized the same design and mechanics. Big Time Gaming was not a huge name in the online gaming marketplace back then, and you have to wonder just how much profit Bonanza was making for its design to be licensed out in this way.

One unfortunate side effect of this sequence of events might be that all other slot developers begin patenting their design innovations going forward, in a way that just wasn’t common previously. You have to question why Microgaming and NetEnt didn’t try and patent many of their own similar innovations – did they not think it would be possible?

The first 243-way slot games, for instance, were immediately copied by other developers without any kind of license fee being required. It remains to be seen if Megaways will end up harming the industry overall, but BTG seems keen to try the same trick again with their newly invented Megaclusters mechanic. If BTG can do it, why can’t everybody else? I know that is what I would be thinking if I were an executive at Microgaming.

Progressive Slots

Undoubtedly, a progressive jackpot slot is essentially just a regular video slot with one additional defining feature. It’s definitely a good thing to separate these games into a different category though because a large portion of a progressive games RTP has to go towards funding the jackpots offered by these slots.

As much as 10% of every bet placed on a progressive slot may go towards funding the current jackpot and seeding the next one, and unless you are lucky enough to be the winner of that progressive jackpot, you are effectively playing a game with 10% lower RTP than pretty much every other video slot out there.

If the idea of winning Powerball-style millions from a single slot spin appeals to you – and let’s face it, why wouldn’t it! – then you may fancy spending some of your time and money playing progressive slots despite the low RTP. Just keep in mind that Powerball-style jackpots come with Powerball-style odds, and your chances of actually walking away with the million-dollar prize could easily be in the hundreds of millions to one range.

Grid Slots

Finally, a grid slot is a type of game that does away with the typical reels and payline mechanics favouring a large grid with payouts for groups of adjoining symbols. Seeing one of these games in action may well immediately remind you of a certain candy-inspired smartphone game, or perhaps one of its endless clones.

The grid will usually be 7×7, 8×8 or 9×9 in size, and groups of between four and fifteen symbols tend to be associated with a win in most of these games. Winning groups of symbols will usually disappear when you win, allowing new symbols to fall in from the top much like a regular “rolling reels” video slot.

These games work in a very different way to regular video slots, so they are deserving of their own category. Most of the top-tier slot providers have now added a grid slot or two to their portfolio, and there are already dozens if not hundreds of really fun grid slots on the games lists of top online casinos.