How are Slot Games Made? – From Concept to Game

05th April3 min read

Have you ever wondered what goes into making a slot game? Months of work by a team of designers and IT guys? Are some slots are made by plugging graphics into standardised game templates, while others involve a full-blown production? Well, you don’t have to speculate any longer! Here is an insider preview of what goes on behind-the-scenes.

Conceptualisation and Design

The first step is deciding the concept or theme. The company may consider the audience’s preferences, which usually differ by geography and channel (mobile or desktop). Sometimes, game companies may partner up with reputed brands and movies – slots modeled after HBO’s Game of Thrones, Universal’s Jurassic Park, Marvel’s superhero series, South Park and Immortal Romance are particularly popular among players. These collaborations usually take longer and cost more, as the slot must reflect the established brand and obtain licensing rights.

The success of a game depends on a combination of few elements – theme, graphics, game mechanics and mathematics. The mathematical element is about creating random wins based on a set of rules. The game maker decides how to balance frequent small wins with infrequent big wins. They must also determine the near-misses or partial-hits; number of free-spins and bonus payouts.

The game mechanics include the different features in each game. The game designers have to figure out every little detail. You can just imagine their conversations – How can we reimagine the Wild symbol work? What are the rules of our mini game? Can we throw away the slot reels and introduce a grid of falling candies instead? How about asking the players to build a castle while spinning the reels?


Once the game concept is in place, the art directors start by drafting the graphical elements. It’s quite like the behind-the-scenes of an animation movie; these guys decide what the characters and background setting should look like, what symbols they should place on the slot reels and so on. The designer would also establish the user-interface layout and produce wireframes that serve as a visual guide for the team. Working in parallel, there are other team members that develop sound and 3D effects; all the extra jazz that enhance the gaming experience.

These are wireframes, or a draft of what the game layout should look like. Then, system developers and graphic designers start putting the games together. Most of the games today are written using the HTML5 programming language, which allows games to be written once and work on multiple platforms. Previously, most games would have to be written twice – one version for desktop players and another for mobile. My colleague Martina has written a separate article on the technological evolution of games. You can imagine how complicated the technology gets, as game servers must handle tens of billions of transactions a year, from all over the world!

That’s a lot of work! How much does this cost?! This process usually takes three to six months. Some bigger productions may take up to 2 years! To throw around some numbers, NetEnt and its 450 employees, producing 36 games in a year. The company spends about £15 million on salaries in a year.

Testing and Verification

The game is also verified by an internal testing and quality assurance process, followed by an independent review and verification. Accredited test institutes like eCOGRA and iTech Labs  would make sure that the random number generator in each game is truly random. In other words, no human or computer should be able to predict the next combination on the slot reels.

These testing procedures continue even after the game is launched to public, to make sure that the game keeps working as it should. The game developer and testing institutes also keep detailed documentation; these facts and changes are then audited by gaming authorities like UK’s Gambling Commission or the Malta Gaming Authority.

Behind the scenes at Betspin: The team tests their gaming platform on multiple devices.

Promotion and Launch!

When the South Park slot launched, casinos gave away lots of free spins!

Finally, the software providers and casino operators work together to launch the game on separate casino sites. When the game is ready for release, both parties also develop special promotions to attract players. Big games usually get extra fanfare; the casinos may offer free spins to try out the new games and bump them to the top on the games lobbies. These big-name games also warrant trailers that give players a sneak peek of the games features. Affiliate sites and magazines like ours would also publish game reviews to promote the new games.

Once the game is in operation, casino operators pay monthly license fees, which is determined by the revenues generated by the game. Now, watch the entire design and development process in action! This video follows the Microgaming team as they develop the Avalon II slot. There you have it! At the end of a long and arduous process, players like you and me will enjoy these games, for months and years to come.

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