Slots have been an integral part of an online casino experience ever since the first one opened its virtual doors at the advent of the digital era in the 1990s. They are immensely popular with the playing public, by far outnumbering any other type of games of chance one can find in a casino lobby. Unsurprisingly, they have greatly evolved from rudimentary 3-reel designs to sophisticated video slots in countless formats with complex math models, intricate graphics, stunning animations, suspenseful bonus features, various free spins rounds and in part huge win potential.
The history of slot machines started in the late years of the 19th century and is continuing to evolve in our modern times. They are a true testament to the boundless creativity, imagination and ingenuity of humankind. You can scroll down for a brief look at the milestones in slot development spanning more than one hundred years.
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And it doesn’t stop there. Simultaneously, we test and review dozens of new and established online casinos where our members and readers can safely play their favourites as well as try all new slots. Feel free to click on any of the tabs that will take you to each part of this guide or use our comprehensive search tool to find the reviews and details about all-time favourites and new online slots. Let’s Play!
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The history of slot machines is the perfect example of how an invention evolves over time from its simple and rudimentary beginnings to a highly sophisticated digital creation. Much has happened in the course of a little over a century since the first slots made their appearance in bars and saloons.
Where early designs were mechanical machines housed in wooden cabinets sporting a single pay line, today’s modern video slots can have well in excess of one million ways to win. Not only that but they will also have a range of random modifiers, bonus features or free spin rounds included in the gameplay.
Such is the popularity that some 70% of all casino revenue worldwide is generated by slot players. No other game of chance comes even close to match that figure. Reason enough for us to take a closer look at the history and developments of the last century.
Liberty Bell – The First Real Slot Machine
The honour for building the first-ever real slot machine goes to a gentleman from San Francisco, USA. Charles Fey (1862–1944), a car mechanic turned inventor, developed the famous Liberty Bell in 1894. Housed in a polished wooden cabinet, it had three reels with painted diamonds, spades, hearts and the Liberty Bell as well as a lever on the side to get them spinning. Hitting three bells gave the biggest payoff, a grand total of fifty cents or what was then ten nickels.
As gambling halls were prohibited in most states at the time, the machines could be found in countless barbershops, tobacco stores, saloons and even brothels. The invention has been pivotal in the history of slot machines and the 3-reels mechanic is still in use today.
Slot Machines Are Electrifying
It wasn’t until the 1960s when Bally developed the first electromechanical slot called Money Honey, that went on to become one of the most popular games on casino floors in Las Vegas and around the world. Another decade passed before Nevada-based Fortune Coin Co introduced the first video slot, a rather monstrous cabinet holding a 19” screen from Sony. Interestingly, the company was later acquired by today’s industry giant International Game Technology Plc, better known as IGT.
Slot Machines are Moving Online
Little will have Charles Fey thought that his invention would once change from a large wooden cabinet to a digital product that could be accessed anywhere on the planet via an internet connection. Theoretically, even astronauts sitting in the space station can play slots at an online casino. All thanks to the marvels of the digital era that began in the 1990s and has since revolutionized the way we communicate, get information, purchase goods and yes, play casino games.
The first online casinos launched in 1996 at a time when our internet connection was running through a simple phone line and broadband services and mobile gaming was still nearly a decade away. The pioneers, game providers and casino operators alike, had to overcome immense challenges to deliver a product that was easily accessible and enjoyable to the point that it could match the experience of visiting a real casino in Las Vegas or anywhere else on the planet. The first solutions were download clients that encompassed all online casino operations. ranging from games to bonuses and payment sections. The initial file was small enough to download in a reasonable time via a phone line while games would be installed consecutively when the player was logged in.
The resounding success of the first online casinos paved the way for quick development to widen the options for operators and players. We have since moved to browser-based and mobile gaming with no download needed. Especially the introduction of smartphones and HTML5 had a profound impact on how we play online casino games. Today, virtually everyone with a mobile phone is carrying a small casino in their pockets.
Obviously, video slots kept evolving over the years with WMS introducing in 1996 for the first time a second screen bonus game on their iconic Reel’ em In slot. This was the same period when online gaming started to emerge, although it was a slow procession at first with Microgaming and NetEnt being the drivers in the early stages. Slots have changed dramatically since, leading to a multitude of format, reels, rows, ways, progressive jackpots, modifiers and features.
Triple Magic (Microgaming) – Immortal Romance (Microgaming) – Bonanza (Big Time Gaming) – Reactoonz (Play’n GO)
Line Video Slots
Gone are the days where slot machines would have a single pay line, be it on three or five reels. Today, we have anything from 3 to 100 lines incorporated in anything from 3×3 to 6×5 formats. The main characteristic of line slots is that in order to score a win you will need to land matching symbols or in combination with wilds along an active pay line.
“Ways” Video Slots
To have 100 lines was never meant to be the maximum or the end of the evolution of video slots. Microgaming was the first to develop and launch the ways game engine with 243 ways to win. The change meant that there was no need anymore to land symbols on a line. Instead, a win is paid as long as matching symbols land on adjacent reels. Thunderstruck II and Immortal Romance are some of the most popular 243-ways slots. That was further stretched to up to 4,096 ways with six reels on games such as the iconic Raging Rhino from WMS. And yet, it was still not the end as Red Tiger Gaming demonstrated on Laser Fruit, which has up to 60,466,176 ways to win.
And then came Megaways. Introduced in 2016 by Big Time Gaming on their Dragon Born slot, it started a new trend in how we play slots and became into an online gaming phenomenon. The immense popularity and success turned BTG into a shooting star in the industry. The highly sophisticated game engine features dynamic reels with no set amount of symbols per reel. Instead, the engine selects a random number of symbol for each reel at the start of a spin, limited only by the maximum ways to win and thus creating virtually unlimited combinations of rows and ways. The standard Megaways engine has up to 117,649 ways while other variants can have 15807, 46656, 200704 and more.
A different type of video slots not relying on pay lines are the grid slots. They started to appear around 2005 with Swedish game studio Play’n GO being the main driver. Instead of spinning reels, a grid slot comes in a defined format e.g. 5×5 and symbols drop from the top at the start of a spin. Landing a minimum number of matching symbols, usually four or five, connected vertically and/or horizontally will constitute a winner. All in the combo are then removed and more symbols drop from the top to potentially start a chain of wins within a single spin sequence. Reactoonz from Play’n GO and Jammin’ Jars from Push Gaming are currently the most popular grid slots.
Did you know that there are currently over 200 game developers, each vying for a spot in online casino lobbies and at the top of the players’ favourites list? While the beginnings of online gaming was dominated by only a handful of suppliers such as Microgaming, NetEnt, Playtech, Rival and RTG, the quick evolution and exponential growth of online casinos has seen a vast increase in studios creating online slots.
Unsurprisingly, we see dozens of new games being released every week into casino lobbies with every developer hoping that their creation will be the next blockbuster slot that has players lining up to take a spin. Needless to say, many are trying but only a few are succeeding. A good part is pure clones of existing games and another part is sheer boring; overall, many will be quickly forgotten and disappear into the deep abyss of wannabe hit slots. Still, the flux of new releases continues unabated as our modern society has an insatiable hunger to be entertained.
An average casino lists between 40 and 50 suppliers while some such as Videoslots offer slots and games from over 100 studios. On average, developers release two new online slots every month, which equates to dozens of new games creations being added on weekly basis to a steadily growing list. Surprisingly, few slots are actually removed, mostly when they reach their EoL, the groovy-sounding acronym for ‘End of Life’ that developers use to mark the termination of one of their games.
GMBLRS has made it a core part of its mission to separate the wheat from the chaff and review only the best online slots that we feel will entertain players and provide good value for money while having the capability to deliver big and mega wins. We receive countless demo slots every week for testing and reviews in addition to having access to many client areas of game developers that allows us to see how a slot plays and what capabilities it has. While we add a good part of the games to our listings, we use our experience of over 20 years of playing casino games to choose only the best new slots that deserve a full review with exact details about paytables, mechanics and features.
The term ‘best online slots’ is a dynamic phrase, simply because it is often a subjective decision as to whether we like to play a specific game. Good marketing strategies by developers also play a significant role. Having the rollout of a new slot well-publicized and promoted by various actors in the industry ranging from casino operators to streamers and reviewers can create such a hype for the release day that players will line up to take the first spins. Nevertheless, if the slot turns out to be a thud it will also be quickly forgotten.
For us at GMBLRS, it is important to look past the hype and keep an open mind when we test a new online slot. Fancy visuals and elaborate animations are usually the norm in our modern times but pretty pointless if the slot is otherwise a thud with unbalanced gameplay, overly long losing spells and poor performing features. Naturally, we distinct between low, medium and high volatility slots as they are built to appeal to different player groups. Both ends and the middle of the spectrum can fulfil their task in such a manner that players feel entertained and enjoy their slotting sessions while also having the chance to hit some sizeable wins.
Our slot tests are much more comprehensive than just a few spins to make sure we get a good feel for the gameplay. While a significant part is quickly set aside due to them being pure clones, poor graphics or obvious lack of an entertainment factor, the remainder has to prove that they can provide that tingling feeling and sense of anticipation when spinning the reels. Just as important is the compatibility for the slot to be equally playable on any desktop, mobile or tablet device.
Only the best new online slots from each day of testing will receive a full review that goes well beyond the statistical data such as RTP, bet sizes, pay lines and others. We complete a full analysis of the random and bonus features, we explain the mechanics at work and jot down the most important parts of the pay table. Taken together, it will allow our members and readers to get a good indication as to what they can expect from a new game.
Most developers and casino operators are offering all or a good part of their slots in so-called Demo Mode. Initially, the idea behind it was to lure land-based casino players to try online slots and hopefully turn them into online gaming fans. It wasn’t always very transparent as some suppliers would crank up the RTP of their demo slots to leave a more favourable impression on potential players. Regulations and voluntary industry memoranda changed that and today demo games must be offered with an identical RTP to their real-money counterparts.
The scope has though remained unchanged in that players can try new or existing slots with fun money, be it to get a feeling for the gameplay, check out the features, test a new slot mechanic or simply have a few rounds without committing any real money. You can find them at most online casinos, on game developer websites and on some affiliate sites that included a demo version into their reviews.
However, some countries have introduced Responsible Gambling regulations that entirely prohibit demo play (e.g. Germany) or require a mandatory age verification check (e.g. the United Kingdom). While it limits access to demo slots, it makes sure that casino games are only played by people who are 18 years or older. A move that we at GMBLRS welcome as part of our commitment to promote Responsible Gambling.