In just two decades since the very first online casinos were launched, the industry has seen phenomenal growth. In 2016 it was estimated to be worth over $44 billion worldwide and it is predicted to almost double in size to well over $81 billion by 2022 – driven by greater internet use and more engaging online games. In the UK, online gambling is the largest single gambling sector – accounting for 33% of the total revenue raised.

But while many people enjoy the casino games by these operators, it’s the slots that generate the highest proportion of online gambling operators’ revenue. It’s thought to be as high as 80% in some cases.

So it’s no big surprise that a great deal of time, investment and effort goes into creating the machines to feed the ravenous appetite of both casinos and their players for new and ever-more exciting games to play.

It’s also led to the emergence of a number of leading slots developers with names like Playtech, NetEnt, and Microgaming leading the field.Let’s look at the technology and teams involved in building a slot game.

The team behind a slot

The team that develops an online slot usually consists of around a dozen people including a game designer, a creative team, mathematicians, server and front-end developers, a game tester and a project manager. Each has a particular role to play in the process – and they’re all involved from the very beginning when the concept of the game is worked out.

This involves using key market research and data to brainstorm ideas for a game. At this stage, there could be one idea or 20, depending on the quality of the data to hand and the people in the room.


Once the concept of the game has been agreed, next it’s over to the creative and product teams to make it a reality. They look at what similar games are out there in the marketplace and see how they can present something different that will attract players.For example, if there’s a game out there that features global landmarks such as the Sydney Opera House or Big Ben, developers might look to include other famous buildings like the Eiffel Tower as a point of difference.


They’ll also think about the mood of the game – and how that will be affected by it being a cartoon or using real-life images. All this is to make sure the game will provide the best possible experience for the player. Meanwhile, the marketers will be using their research and data to advise on which color schemes, fonts, and audio elements will work best for the target audience.

It’s at this point that the tone and feel of the new slot are decided upon. Often this is rigidly dictated by the nature of the game. For example, if it features lucky leprechauns leading players to pots of gold it will most probably be whimsical in nature.

But if it’s a game like Treasure Fair, which is set in a fairground there would be the choice of making it fun or, as is the case, a little scary too.

It’s been said that the current generation of slots has also taken their inspiration from the world of video games. So it’s at this stage that a player’s journey through the slot is mapped out and the ways to create the very best player experience are defined.

Once the overall theme and structure of the game have been established, it’s time for its features to be mapped out. These include everything from the visual style it will have to the number of reels and win lines it will feature.

There are also the bonuses to be considered as well as whether it will have a progressive jackpot, not to mention what percentage payout the game will offer.

If the game has a corporate tie-in or is based on a film, the team will have to make sure brand guidelines are used as part of the development. As part of this process, they’ll have to immerse themselves in the visual identity of this brand.

While this may be a challenge, it’s often easier this way than to create a whole new game from scratch – because at least there’s some creative (and a point of difference) to begin with.

3D rendering

Depending on the quality of the game, developers may use 3D rendering techniques during the design stage. This usually begins with drawing up a wire-frame model which outlines the edges of the 3D shape, before gradually building on this foundation with extra colors and details until it becomes a solid state (as shown above).

The Variance System

One of the ways developers can appeal to a target audience is by considering where the game they’re designing falls in the variance system, which segments different types of the game based on the type of payouts they provide. As part of this process, the development teams must decide whether the game is:

  • Low-Risk Variance, which is designed to appeal to a wide swath of players looking to play for as long as possible, with a great number of winning combinations.
  • Medium-Risk Variance, which offers both high and low jackpots and typically attracts players through bonus feature and numerous in-game winning opportunities.
  • High-Risk Variance, which offers the best jackpots to players, but also provides reduced chances of winning per spin.

Random Number Generators

 Each type of games is underpinned by random number generators, which are at the heart of keeping the games fair. RNGs work by using an applied algorithm that randomly chooses numbers, which are connected to the symbols the slot gamers see on screen.

Understandably, it’s almost impossible to find out how they work, as there’s robust security behind them. The most reputable online casinos have proprietary versions of them to ensure their dependability – despite there being many slot machine builders available online.

While there is nothing players can do to change the outcome of an RNG, there are certainly many approaches that will help players get the most out of slot games – including this leading online casino’s guide to how to win at slots.

The ultimate test

Throughout the process of developing the slot, it’s also subjected to frequent testing to ensure that any glitches are eliminated as soon as they are spotted as to ensure that it is playing in exactly the way that it’s meant to. Then, after a process that takes around a year on average, it’s time to release the slot into the world. However much thought and planning have gone into it and however appealing it is on paper, this is the acid test. It could be an immediate hit, or it could be a little disappointing. It’s only when players get the chance to spend their own money on a game that its real appeal will be known.

With all the time and effort that has gone into its development there’s no doubt that it’s a high stakes game but for the successful slots, the rewards can be huge as they’re playing around the world and round the clock too. In some cases, just like Hollywood blockbusters, they even spawn a sequel or two – and that has to be every slots developer’s dream.

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