Slots games are the most prolific games in most casinos today. Straightforward in nature the player simply places a bet, the reels spin and the results of the round are displayed. Unlike Table, Card and Video Poker games, Slots games do not depend on any real world device that imply a natural probability (i.e. the majority of people know that the chance of receiving a 5 when rolling a 6 sided die is 1 in 6) and instead will use a large variety of different symbols. This allows the game manufactures to create a wide range of game settings and House Edge values within the same game without ever misleading a player as to the likelihood of a specific event.
History of the Slots Machine
Originally known as the One Armed Bandit due to the large leaver – or arm – on the side of the early machines, the nature of gambling combined with the traditional high House Edge involved in Slots games often (understandably) left player feeling robbed after play.
The first Slot type game was introduced to New York in the late 1800’s by Sittman and Pitt. This machine used 5 ‘Drums’ (reels) that displayed playing cards. The results of the round were then determined by the strength of the poker hand the player received. Unlike modern machines this game didn’t payout money and instead when the player received a good poker hand while playing the machines – which as a standard were located in bars – they would be entitled to various products offered by the bar.
The first true slots machine – that paid out winnings in cash – arrived in the late nineteenth century when Charles Fey developed the Liberty Bell. The Liberty Bell machine simplified the earlier card based machine by dropping down to 3 reels and using fruit symbols and numbers instead of cards. One of the symbols used was a ‘Liberty Bell’, hence the name. 3 of the Liberty Bell symbol on a line also represented the highest possible payout. The lower number of reels meant that there were less possible winning combinations to account for, making the mechanics of automating the payout system far simpler.
The ‘Bell’ design proved so popular that many other groups stared producing similar machines with Bell symbols.
In many US states at this point in history gambling was considered illegal. To get round this prohibition early machines often gave out fruit flavoured chewing gum rather than cash prizes, hence the name ‘Fruit Machines’. This practice has long since been abandoned with cash risked being paid off with cash returns.
The original slots machines had either 3 or 5 reels – reels being the long strips of symbols that rotate vertically when the machine is played – and showed one symbol off of each reel. These reels had a set pattern of symbols, often different on each reel. As the reels were physical objects there were only so many combinations of symbols that could come out and this created difficulty – as the reels were equally likely to stop on at any specific position, even if set so that there was only one way for the top paying combination of symbols occur, without having unfeasibly long reels, the top paying combination would still occur far too often to allow large jackpots. With 10 symbols on each reel the jackpot combination would occur approximately once in every 1000 spins. The first solution to this problem was to include more symbols on a reels – this did help but did not entirely solve the problem as what the designers really wanted to do was offer jackpots worth millions of dollars.
With advances in computer technology in the 1980’s, slots games moved away from using physical reels which were limited by their size and the number of symbols that could be fitted on them to instead use ‘virtual reels’. A virtual reel could be as long or short as the game designer wished, by using electronic displays rather than physical reels computer code could define the order of the symbols on each reel and the length of the reel. No longer limited by the physical space required to fit the symbols on, each symbol can now appear in as many positions as the programmer likes allowing the odds of the top jackpot combinations to be adjusted to allow for very large jackpots. Since that point slots machines have rapidly become the most popular game in any casino.
Modern slots machines have between 3 and 9 reels (possibly more, but 9 is the limit we’ve encountered online – some games do treat each symbol position as a separate reel which does result in technically more reels but the player will still see between 3 and 9 vertical strips) with 5 reels being far and away the most common. In general you will see be able to see between 1 and 5 symbols on each reel with between 3 and 5 being the most common.
Differing Reel Layouts
While the rectangular single game reel is by far the most common type of game on the market at the moment, there are new and inventive styles of games appearing all the time. Some of the more notable examples are detailed below;
Multi-Game – The multi-game format places several of the same slots game in a grip on the screen (most commonly 4) allowing the player to play multiple instances of the same game at once.
Varying Reel Sizes – Most slots games have the same number of symbols on each reel, for instance a 5×3 grid. Notable games that have moved away from this format are Siberian Storm, Star Trek Against All Odds and Sumatran Storm from IGT and Reel Rush from Net Entertainment which offers a diamond shaped reels, with less symbols at the extremities, Wolf Rising from IGT that has a double stacked reel (5×8) and DaVinci Diamonds Dual Play and Masques of San Marco from IGT that have 2 sets of reels stacked on top of each other.
Midas Millions from IGT also uses hexagonal symbols in a honeycombed set of.
Multi-Spin – The multi-spin games provides a similar experience to multi-hand Video Poker game where the player is given an initial set of symbols and selects which symbols to keep. The discarded symbols are then replaced. With many of these games the held symbols are repeated on to multiple instances of the reel allowing more than one game to be played in a single round. Unusually for slots games, due to the player decisions, these types of game do have an optimal player strategy. Most software providers have been reluctant to release these strategies but accurate mapping of the reels would allow for derivation of the correct strategy. The Multi-Spin games that we are aware of are as follows;
3 Reel Hold Up – IGT (click here for optimal strategy)
Enchanted Forest – Microgaming
Goblin’s Cave – Playtech
Ocean Princess – Playtech
Tropic Reels – Playtech
Ugga Bugga – Playtech
This list is far from exhaustive and no doubt many new variations will arise in the years to come.
The first slots machines had one payline positioned horizontally across the middle of the reels. Only symbols that fell on this line would be considered as part of any winning combination. Modern machines often use far more paylines which are defined as a path across the reels where if you receive two or more matching symbols in a row – typically starting from the left side of the reels – on an active payline (depending on the game and the symbol I can require more matching symbols) a win in generated.
Slots games will often have their own method of how exactly the paylines work. Most machines will define the paylines in the paytable and pay only combinations of matching symbols that occur left to right along an active payline (one the player has chosen to wager on). However there are variations on this. Some games will pay combinations out of order (with non-matching symbols in between) while others will pay right to left (or both left to right and right to left).
A recent development in online slots games has seen the introduction of the ‘Multi-Way’ pay system. The Multi-Way system is offered by all the major online slot providers but we believe that it was first introduced by IGT. In Multi-Way games, rather than using defined paylines, any 2 or 3 – depending on the game – matching symbols anywhere on adjacent reels starting from the left side of the screen results in a win. This is the equivalent of 243 paylines where 3 symbols are required and 1043 where 2 symbols are required.
As with some card games, a Wild symbol on a slots machine can count as any symbol on the reels. This means that even though the symbol doesn’t match, it is considered to and can be considered a different symbol on different paylines (if the Wild symbol happens to fall in a position where it is on multiple paylines). Often Wild symbols will associate a multiplier to the standard win making the combination worth more if it involves a Wild symbol. Sometime the multiplier is fix and for other game the multiplier is randomly decided at the end of the spin.
There are many different variations on the traditional Wild symbol, some of the more common we’ll discuss briefly.
Expanding Wild Symbols – Some games – like Cryptologic’s King Kong – have what are known as expanding wilds. When you receive a wild symbol – sometime any wild symbol but most often on a specific reel or in a specific circumstance – the wild symbol expand to cover the entire reel making a full Wild reel.
Stacked Wild Symbols – Other slots games have stacked wild symbols, where the wild symbols are stacked one on top of another on the reels and as such every symbol on one or more reels can end up being wild.
Multiplying Wild Symbol – is a Wild symbol that will turn other symbols into Wild symbols at random – a good example of this type of wild symbol is the Fire and Lightening wild symbols in Net Entertainment’s Frankenstein slots game.
Moving Wild Symbol – One of the newer and more inventive wild symbols we’ve come across is the wagering wild from Net Entertainment’s Jack and the Beanstalk slots game. During this game when you receive a wild symbol anywhere on the reels, you are paid and then the wild is moved one position to the left and the reels are re-spun at no extra cost to you. This keeps going until the wild symbol moves all the way over to reel one. There are many more variations on the Wild symbol that you’ll encounter as you explore different online casinos.
Locking Wild Symbol – The Locking Wild symbol is one that when received will lock in position for a number of spins. This type of Wild symbol in more common on Free Spin bonus features. Good examples of Locking Wild symbols can be found in IGT’s Ghostbusters game or Net Entertainment’s Crime Scene game.
There are some exceptions where wild symbols are not considered as replacement symbols which we’ll cover below.
Scatter symbols are very simple to understand – rather than being required to have them in a row on a payline, simply having 2 or more (depending on the game) anywhere on the reels qualifies you for a payout. In almost all cases, Wild symbols do not substitute for Scatter symbols. Scatter symbols are common in most online games now and are often used to trigger bonus features.
Bonus features were the single biggest factor in raising the popularity of slots games. The basic idea is that some trigger within the game suspends normal play and initiates a second tier game with a far higher than normal change of a substantial wins and no further requirement for the player to wager more.
Free Spin bonus features – Free Spin bonus features are one of the most common types of bonus feature offered in Slots games. The basic premise is that when triggered – most often when 3 or more of the same Scatter symbol appears anywhere on the reels during a single spin – the player is awarded a predetermined number of spins on the game without having to make any more wagers. As a standard these spins are played at the same number of coins and paylines as the bet that triggered the Free Spins.
Many games will play the free spins on a separate set of reels that offer an increased chance of payoff for the player or simply fit a different aspect of the theme of the game in question.
It is common for additional benefits to be awarded during the Free Spins. Commonly seen additions include multipliers that are applied to all wins (these can be consistent throughout the free spins or vary from spin to spin), additional Wild symbols or unique Wild symbol behaviour (Locking/Expanding wilds) or additional scatter symbols.
While most Free Spin features are triggered by specific symbols appearing on the reels in a single spin, or occasionally randomly at the end of a spin, some recent games have built in ‘bank’ features that allow the player to earn their way towards free spins. Examples of this type of feature can be found in Microgaming’s Scrooge or The Dark Knight Rises and Net Entertainment’s ‘Robin Hood Shifting Riches’.
These bank style Free Spin features are generally played out on the average coin size and lines played during the earning of the feature, but occasionally they have been set to play at the coin size and paylines of the last triggering spin. This has led to some substantial issues involving Microgaming and RealTime Gaming softwares where players have played minimum bets while earning the majority of the feature then moved up to maximum bets to trigger the last part of the feature, resulting in some smart players winning substantial sums of money that the casinos involved were unhappy to pay.
Pick Bonus Features – Pick bonus features will generally take the player to a new screen showing a selection of objects or symbols connected with the theme of the game being played. The player will them get to either select a set number of them with each object awarding a prize, or continue to select objects until a specific symbol or alert is found that ends the bonus feature. A good example of this type of feature would be Microgaming’s ‘Tomb Raider Secrets of the Sword’.
While the Free Spin and Pick bonus features are by far the most commonly found Slots bonus features there are a huge variety of bonus features on the market. Below are some of the games with the more interesting bonus features we’ve come across that haven’t been mentioned above;
Leander Games – Megadeth
Net Entertainment – Evolution, Elements – The Awakening, Aliens, Scarface, Magic Portals, Jack Hammer 2 – Fishy Business
IGT – Monopoly Plus, Dungeons and Dragons Treasures of Icewind Dale, Transformers – Battle for Cybertron, Dungeons and Dragons Fortress of Fortune
Cryptologic – Time Machine, Horns and Halos, Call of Duty 4 – Modern Warfare
Playtech – The Avengers, Spiderman – Attack of the Green Goblin, Pink Panther, X-Men, Alien Hunter
Rival – Rock On!
Betsoft – Greedy Goblins
Microgaming – Battlestar Galactica, Avalon II – Quest for the Grail, Immortal Romance, Gold Factory
Commonly associated with Slot machines is the Progressive Jackpot. These vary from the standard payouts offered by slots machines in that they are constantly rising until such a point as a player hits the jackpot at which point it drops back to its ‘seed’ value (the minimum value provided by the providing game network).
Progressive jackpots in general offer the player the chance to have ‘life changing’ win sizes which are far larger than those offered by other machines but compensate for this providing far lower win frequencies at the lower end.
The jackpots are built up by player contributions. Each spin played on the machine a percentage of the wagered amount will be added to the Progressive Jackpot. This means that the longer the Progressive Jackpot goes un-won the larger it becomes.
It is standard for Progressive Jackpots to be networked – i.e. every casino offering a game will contribute to the same jackpot pool held by the network provider and when the jackpot is won the network provider then pays the win rather than the specific casino.
Unfortunately certain unscrupulous online casinos have started building in terms and conditions stating that Progressive Jackpot games will be paid out in instalments. The intention behind this is that once the network has paid the casino for the win they can then hold onto these funds for longer (giving them a substantial free capital boost) and the player, forced to leave a substantial body of winnings in the casino, is likely to lose a significant proportion of their win back to the casino before the win is paid out. This is absolutely unacceptable and unethical behaviour. As the casino does not pay the win it is not within their rights to withhold payment of the win. Players should be aware of casinos that engage in this practice and avoid them.
It should also be noted that games featuring Progressive Jackpots – once the possibility of winning the jackpot is excluded – usually result in the player playing a very expensive game compared to other non-Progressive Jackpot games.
The House Edge of slots games is difficult to derive unless the software provider publishes this information with the game. Generally when this happens the software provider will publish a ‘Return to Player’ or ‘RTP’ figure. The RTP is just the reverse of the House Edge. While the House Edge tells you how much you will lose of every 100 credits wagered (on average) the RTP tells you how much of your 100 credits will be returned. To find the House Edge subtract the RTP figure from 100.
Theoretical and Real RTPs
You’ll regularly see discussion on slots forums of Theoretical RTP (tRTP) and Real RTP (rRTP). This is simply the difference between the short and the long term results of the game.
The rRTP is the return the game has provided to players in the recent history. While this figure does accurately reflect the performance of the game over a defined period, it has no bearing on how the game will perform in the future.
The tRTP is the return the game will provide over the long term (millions of spins). While the variance of most slots games is high making short term predictions about results difficult the tRTP has far more relevance when it comes to estimating the results to come in the future.
Online Slots RTPs
Below you’ll find the top 10 slots games for most major providers defined by the best House Edge;
|Vampires vs Werewolfs||2-5%|
|Fortune 8 Cat||3.01%|
|The Italian Job||5.00%|
*Many Amaya games appear to have 3 different House Edge settings. These range from very high (10%+) to low (3% or less). We have excluded these games from this list as it is impractical for players to ascertain which setting they are playing against.
|Good Girl, Bad Girl||2.20%|
|At the Copa||2.58-2.6%|
|After Night Falls||2.7-2.73%|
|The True Sheriff||2.97-3%|
|Back in Time||3.00%|
*Betsoft do not currently publish the House Edge information for their slots games. The figures in the above table have been sourced from various online casinos that have independently published their figures. As such these games may have variable settings explaining the range in numbers.
|Reel in the Cash||2.00%|
|Rags to Richs||2.05%|
|The Flash - Velocity||4.5-4.53%|
|3 Reel Hold-Up||1.94-6.28%*|
|Wheel of Fortune - Triple Action Frenzy||3.00%|
|Monopoly - You're in the Money||3.22-5.97%|
|Dungeons and Dragons - Treasures of Icewind Dale||3.48-6.94%|
|Transformers - Battle for Cybertron||3.53-7.39%|
*3 Reel Hold-Up requires an optimum strategy to reach the lowest House Edge. This can be found in the game help file.
|Retro Reels - Extreme Heat||2.50%|
|MegaSpins High 5||2.57%|
|Scoop the Cash||2.93%|
|Multi-Player Wheel of Wealth Special Edition||2.94%|
|5 Reel Drive||3.05%|
|What A Hoot||3.06%|
|Bust the Bank||3.25%|
|Max Damage Alien Attack*||3.29%|
|Kings of Cash||3.32%|
|Robin Hood Feathers of Fortune||3.37%|
|Age of Discovery||3.38%|
|Kung Fu Monkey||3.39%|
* Max Damage Alien Attack is a skill based arcade game. It’s presumed that you need to play at optimum levels to reach the quoted House Edge figure and that weaker play will result in a higher House Edge.
* We have included a far longer list of games for Microgaming as many of the above games are only available at download Microgaming casinos and we wanted to ensure that players could find information on the best games to play at instant play Microgaming casinos as well.
|Net Entertainment||House Edge|
|Kings of Chicago||2.20%|
|Jack Hammer 2 - Fishy Business||2.90%|
* These games are likely to involve a strategy to reach the stated House Edge.
** Fishy Fortunes operates a progressive jackpot explaining the range of possible House Edges
* These games involve some degree of skill or strategy to reach the optimum House Edge.
** Cinerama involves a Progressive Jackpot so presumably this House Edge figure is only accurate for the highest Progressive Jackpot levels.
*** Golden Tour has the ‘Dollar Ball’ side bet. Players should avoid this bet as it’s very expensive.
We do not include any figures for Realtime Gaming casinos as we are not aware of any reliable source for this information. It is believed that Realtime Gaming slots games have 3 possible settings – 2.5%, 5% and 8.5%.
|Cosmic Quest - Mystery Planets||1.05%|
|Reel Crime - Art Heist||2.97%|
|Watch the Birdies||3.71%|
|Wheel of Cash||3.71%|
|Scary Rich 2||3.73%|
|Reel of Fortune||3.79%|
We do not have any information about the House Edge of the slots games offered by Saucify.
We do not have any information about the House Edge of the slots games offered by TopGame.
Reel Mapping, Variance and Simulation
What defines the House Edge of a Slots game is the Reel Map – that being the layout and frequency of occurrence of different symbols on the reels. For instance and for obvious reasons, Wild symbols are usually a lot more valuable to the player than other symbols.
Where the Reel Map can be established it is a relatively simple task for anyone with reasonable programming skills to take that information and simulate the game and confirm the House Edge settings and variance (size and frequency of different wins and losses) of the game. With some software providers the Reel Map can be read from the game code, but the majority of major providers encode this information to prevent players from obtaining it. In these situations the only way to obtain the reel map is by recording hundreds of thousands of spins worth of information.
It should be noted that many slots games use different Reel Maps for each reel, making accurate mapping more complex.
Over the next few years, resources allowing, we intend to obtain the Reel Maps and simulate the House Edge and variance for the most popular slots game from the major providers. This is a major undertaking and will be resource intensive.
Below you can find a simulator for the games that we have Reel Maps for already.
Amusements with Prizes
Amusements with Prizes (AWPs) are a variation of the standard slots game. With standard slots games each spin is entirely independent of the last. When you see casinos advertising which games are “hot” or “cold”, this is baseless superstitious nonsense. The game may have paid out more or less than expected within recent history but this offers no insight as to what the game will payout in the immediate future.
AWPs are generally different in this respect in that they will respond directly to recent payouts (or a lack thereof) by loosening or tightening up to force the game back towards its theoretical RTP.
Offline these types of games are generally found in pubs and bars in the UK and can be beaten by skilled players, though it should be acknowledged that a large number of players that play AWPs regularly ‘think’ they can beat the game but are losing money in the long run. The combination of alcohol and gambling only serves to reinforce the conformation bias most people are naturally inclined to, meaning that the wins create far stronger memories than the losses and results are not tracked accurately.
Online we are aware of several games at Microgaming casinos that are advertised as ‘AWPs’ but cannot confirm whether or not these game perform as true AWPs or simply a different form of slots game. Alongside this, offline each AWP functions independently based on the results of that specific game. Online would these games function independently or as part of a network? If the latter the volume of play across the network would quickly level out the short term fluctuations making the games force to tRTP irrelevant.
Myths and Intended deceptions
Regularly when playing slots you may feel like you are receiving a lot of “near misses”, seeing valuable symbols line-up one position or reel from a stop that would have resulted in a large payout. This type of occurrence leads players to believe certain things that are not true.
Firstly, past results have no impact what-so-ever on future spins. Even if the observed near misses were genuine (which they’re likely not) the give no insight into what will occur if you continue to play.
Likewise, a run of either positive or negative results gives no indication of a machine being “hot” or “cold” or “overdue” for anything. These terms imply the ability to predict the future based on the short term past results of the game. If this was a possibility no casino would stay in business. Every spin is independent from the last. Terms like hot and cold, overdue or streak are only applicable after the streak has already happened.
Further to this, most slots games are designed with the intention of making the player feel like they just about hit something good. On a psychological level this near reward is a good way of sustaining player interest and ensuring you keep playing.
When playing any slots game it’s important to remember that the sounds and visuals after you click the spin button are there solely for entertainment purposes. The moment you click that spin button the result has already been decided. The animation services only to build tension and expectations.
Winning Strategies for Slots
Offline slots tend to differ from their online cousins in one substantial respect – the House Edge of online slots tends to average at around 5% whereas offline slots regularly run with House Edge figures in excess of 10%. This prohibitively large tax on the player makes winning in any form against offline Slots games exceptionally challenging.
This said smart players have been known to utilise slots club promotions and most notably Progressive Jackpots to gain an advantage over slots games. If a player can determine at what jackpot level a game becomes a positive expectation play and then, using a team of players, lock-up the machines associated with the jackpot (have one player on each machine), they can play until the jackpot is won. Technically there’s no requirement for a team of players, a player could play by themselves and still be playing with an edge, however if other players can be prevented from playing, and potentially winning the jackpot first, the variance inherent in this type of play can be substantially reduced.
Despite typically having a higher House Edge that the Video Poker and Table games available online, in the modern environment Slots games are often the optimum choice for the smart player. The high volatility of slots games can turn even relatively modest bets, when upfront bonuses are taken, into an advantage situation for the player. The main drawback of this style of play is the large bankroll required to sustain play through the variance. Given the extended losing streaks (performing below theoretical expectation) that can naturally occur, relatively commonly lasting in the tens to hundreds of thousands of spins, and the large volume of play it takes to reach the theoretical expectation, a very large pool of funds needs to be available to weather these periods and last through to the long term.
Alongside this, slots games are prone to generating lots of smaller loss followed by a substantial win. Given this tendency towards sizable wins the risk to the player from disreputable casino finding reasons not to pay when they win is substantial.
It should be noted that online advantage play is not specific to Slots and many other games can be played profitably online if the player is familiar with the correct strategies to use. For more information on beating online casinos see BeatingBonuses.com.