How do the reels 'spin' on an online slot machine?

Imagine you are playing the seminal jackpt slot Mega Moolah. You are playing the base game and hitting the spin button, hoping that one of those spins will eventually trigger the Jackpot Bonus Wheel and a chance at landing one of the four progressive jackpot prizes on the slot.

That could even be the Mega Jackpot, the one worth at least a million, if not considerably more. At the time of writing the jackpot is worth £5.25 million.

So the question here is, when you are hitting the spin button on a modern online slot, are you actually aware of the process that is happening within the game mechanics itself that will decide what each symbol is that you see on the reels and whether your spin is a winner or not?

It is tempting to think that slot games online are just programmed versions of the mechanised and electronic games you used to play in your youth, but in actual fact, they are very, very different. Before we learn a little about how the reels actually spin on a modern online slot, let's first examine how things used to be.

The first age of slot gaming

Pretty much from the advent of the very first slot games at the end of the 19th century, through to the 1970s, slot games pretty much followed the same pattern. The games were mechanical contraptions in the main, based on a series of drums or reels, onto which were painted symbols. These reels would spin and using a series of gears and cogs, the reel would then display a symbol on the pay line.

If the symbols matched up, you were a winner, If they didn't, you were a loser. The fact that these early reels had a relatively small number of potential combinations available to them, meant that these particular slot games only tended to pay out smaller amounts.

It was only with the advent of electronic and then microchip technology that saw the number of potential combinations on a spin increase. Initially this was achieved by having more than three reels available on a game, or increasing the size and number of symbols on a reel. However, it soon became apparent that by doing away with the notion of a physical reel, and moving to a virtual one, would offer far more scope for bigger slot games, with much higher jackpots.

That's because as soon as slots moved away from a physical reel and into a 'virtual' reel, the number of possible combinations on a slot is increased hugely as the slot can decide what spins produce what symbols in a different way.

This brings us neatly into the modern era of slot games where the key piece of programming for deciding what turns up on a reel on any spin is the Random Number Generator.

The modern age of slots - Random number generators

When slot gaming became controlled by a microchip and then eventually moved online, the random number generator (RNG) became the most important part of the slot. As the name suggests, the RNG works by a process of generating a random number on each spin. For each random number generated, there is a pattern of symbols which are the ones that will be displayed when that number is selected.

Some of the selections generated by the RNG will therefore be winners and some will also be losing spins. However, it is the proportion of these winning spins, the size and number of wins available and how many potential random numbers can be generated by an RNG, that are the crucial factors in determining whether a slot is a higher variance game, or lower variance game, or something in between.

Obviously, it stands to reason that there are a far greater number of lower value winning spin combinations on a modern slot than there are higher value wins, or potential jackpot wins. But what sort of proportions are we talking about here?

Well the answer is quite daunting as the modern online slot RNG will have at least millions, if not billions of potential combinations possible. Of those potential spins, a significant number of them will be winning spins, however the majority of these winning spins will be lower value spins, with fewer mid-range winning spins and just relatively few higher value spins. There may only be one or two potential jackpot wins out of millions or billions of combinations.

Just how many potential combinations there are, what proportion of them are winning spins and the exact chance you have of winning the top prize on a slot, is a closely guarded secret on many games. While the RTP gives you an idea of how much a slot will pay out of the money it takes in over its lifetime, it is worth remembering that it does not mean that it is indicative of your chances to win on every spin.

For example, a slot with a RTP of 96% does not mean on every spin, you have a 96% chance of winning, or even that if you have 100 spins, for £1 per spin, you will win back £96 on average. The RTP is based on billions of spins, not a small sample (and by small we are talking about anything less than a million spins).

Therefore a slot RTP percentage is only indicative of the long term payout standard of the slot. For short term sessions, players will actually experience wild fluctuations compared to that amount, some will earn far less back from their play (due to the house edge), while other more fortunate players can make a profit. For the very few, a jackpot win, such as the recent CA$8.1 million win on the Mega Moolah slot, means that they will make a massive profit.

Why have reels when modern online slots don't actually need them?

If the modern online slot is not decided by a reel, then the question is why do so many slots still use them in their game? Well the answer to this I feel is simple. We are more comfortable as slots fans seeing reels spinning to decide the win. Tradition holds it that spinning reels is how wins are decided so these factors are the methods chosen to display the wins on modern online slots.

Some slots, notably those with the Rolling Reels feature (such as Football Star or Jungle Jim El Dorado) are presented without spinning reels, but dropping blocks and these games are among the first to move away from presenting slot games on reels.

I can't ever see a time when slot games are taken away from being presented on reels. It is too ingrained in slot players to do away with them entirely. However, with new game design and new innovations, there may well be more games that come along that do not have reels to play with.

But you can bet that each one will have the RNG as the beating heart of the game.

Byline: This article was published by Mega Moolah expert Henry. Media and other enquiries.

Next article: What is your favourite online slot bonus feature?