"Slots" are an electronic version of traditional slot machines. The mechanism is simple: you place a bet, press a button, and virtual reels start spinning. If a certain combination appears after the reels stop spinning, you win something. Each play is called a spin.
Let's be honest: the design of slots is unlikely to be called beautiful, and certainly not in line with modern minimalist trends. But why do these bright, epileptically flashing images make users play again and again?
Let's figure out what's going on.
Let's be honest: the design of slots is unlikely to be called beautiful, and certainly not in line with modern minimalist trends. But why do these bright, epileptically flashing images make users play again and again?
Let's figure out what's going on.
Magic of Numbers
In psychology, there is a concept of the "magic number": 7 ± 2. This refers to the number of items a person can hold in their working memory at once. If there are more items, the brain can become overwhelmed and "freeze," unable to process information and make decisions. At such moments, attempting to reach the person is like making random mouse clicks on a computer monitor that suddenly lags.
Now, think about online casino slots. The eyes are bombarded with visual stimuli: everything glitters, spins, flies, and shimmers. There are numerous distracting elements, and each one competes for the user's attention. Their gaze constantly jumps between the flashing objects, trying to "grasp" onto something relatively static, like the Spin button, for instance.
Now, think about online casino slots. The eyes are bombarded with visual stimuli: everything glitters, spins, flies, and shimmers. There are numerous distracting elements, and each one competes for the user's attention. Their gaze constantly jumps between the flashing objects, trying to "grasp" onto something relatively static, like the Spin button, for instance.

UX/UI design and Pavlov's dogs
One of the secrets of successful slots is a clear interface. Everything that serves as a Call-to-Action (CTA) should stand out, especially registration, deposit, and spin buttons.
Take care of your benefit and user comfort: the more convenient it is for them to click the button, the higher the likelihood they will do it.
According to the WCAG guidelines for web developers, the optimal button size on desktop should not be smaller than 44x44 CSS pixels. For mobile devices, different companies provide different recommendations:
Keep in mind that the interface should display well both on computers and phones. When designing for the mobile version, remember that the user is likely to hold the device with one hand. This means that CTAs should be positioned in a way that allows them to be easily reached by the thumb of the hand holding the phone.
What else attracts users to slots? The tense atmosphere. Graphics, design, and sound design contribute to it. Casinos do not emphasize small "wins," otherwise, the user would quickly get their dose of dopamine and leave. It is much more effective to create the illusion that there was no victory at all. Through color, animation, and sound, only significant wins are highlighted, which will delight the user to such an extent that they will continue playing for the chance to experience that positive emotion again.
Take care of your benefit and user comfort: the more convenient it is for them to click the button, the higher the likelihood they will do it.
According to the WCAG guidelines for web developers, the optimal button size on desktop should not be smaller than 44x44 CSS pixels. For mobile devices, different companies provide different recommendations:
- 10x10 mm or ≈37.8x37.8 px (MIT Touch Lab)
- 44x44 px (Apple)
- 48x48 dp, which is equal to 48x48 px (Google)
Keep in mind that the interface should display well both on computers and phones. When designing for the mobile version, remember that the user is likely to hold the device with one hand. This means that CTAs should be positioned in a way that allows them to be easily reached by the thumb of the hand holding the phone.
What else attracts users to slots? The tense atmosphere. Graphics, design, and sound design contribute to it. Casinos do not emphasize small "wins," otherwise, the user would quickly get their dose of dopamine and leave. It is much more effective to create the illusion that there was no victory at all. Through color, animation, and sound, only significant wins are highlighted, which will delight the user to such an extent that they will continue playing for the chance to experience that positive emotion again.

Here, it's just like with Pavlov's dogs: one stimulus, and the user will keep pressing 'Spin' again and again in anticipation of the reward. Especially since they already know what will notify them of the 'cosmic win.
Color as a chimera
You can talk a lot about the psychology of color, and you could even write a separate article about it. You probably know that each color has its own meaning, and marketers and designers take it as an axiom. There is some truth in this: color indeed evokes specific associations in humans. These associations can vary depending on various factors, such as a person's profession. A farmer might associate green with fields and freedom, while a banker might associate it with money and the enclosed space of an office.
To answer the question of why slot design attracts players, we can refer to this table. It indicates the meaning of each color. We analyzed slots on gambling platforms and concluded that the following colors prevail in their design: blue, purple, red, and yellow. Through straightforward reasoning, we can find a correlation between color, user emotions, and the time they spend playing.
To answer the question of why slot design attracts players, we can refer to this table. It indicates the meaning of each color. We analyzed slots on gambling platforms and concluded that the following colors prevail in their design: blue, purple, red, and yellow. Through straightforward reasoning, we can find a correlation between color, user emotions, and the time they spend playing.
- Red: Excitement, courage, dominance, energy, passion, power
- Orange: Abundance, fun, liveliness, safety, energy
- Yellow: Alertness, confidence, optimism, self-esteem, energy
- Green: Calmness, comfort, balance, harmony, hope
- Blue: Competence, intelligence, logic, security, trust
- Purple: Authenticity, dignity, exclusivity, luxury, high quality
- Pink: Charm, liveliness, sincerity, softness, calmness
- Black: Dignity, efficiency, elegance, strength, wealth
- White: Peace, clarity, down-to-earthness, honesty, sincerity
If the theory of color is not enough, let's turn to physiology. In casinos, it certainly plays no less of a role. In the human eye, there are cones responsible for color perception.
When you stare at one color for too long (especially a bright one), the cones get tired and switch to another color. During this time, you shift your gaze from one colorful object to another and see spots that remain after viewing the first bright object. These colors are imaginary: the eye doesn't see them; the brain does. They are called afterimages (or chimerical images).
What does it have to do with casinos? Let's conduct a simple experiment. Look at the image below for a few minutes, and then shift your gaze to a white sheet of paper. If you see colored spots on it - congratulations, your cones got tired.
When you stare at one color for too long (especially a bright one), the cones get tired and switch to another color. During this time, you shift your gaze from one colorful object to another and see spots that remain after viewing the first bright object. These colors are imaginary: the eye doesn't see them; the brain does. They are called afterimages (or chimerical images).
What does it have to do with casinos? Let's conduct a simple experiment. Look at the image below for a few minutes, and then shift your gaze to a white sheet of paper. If you see colored spots on it - congratulations, your cones got tired.

And now, imagine that the user regularly looks at a screen where contrasting colors constantly change, illuminate, and shimmer. The cones remain in such a state of shock that after the game, the user sees afterimages of colors on light monochromatic objects for some time. This is a vivid (in the most literal sense) reminder that it's time to return to the slots and play again.
What do the experts say
We talked to representatives of affiliate programs specializing in gambling to understand which design is currently trending and which one is time to forget
How to determine which slot design is most popular among players?
We determine popularity through internal analytics. Often, it's settings with animals, space themes, historical and cultural storylines, and, of course, treasure hunting.MostBet Partners
There are various factors. One can compare the number of bets in slots with different designs, rely on players' preferences in a specific region, experiment with slot positioning, or conduct surveys. However, the conclusions can only be based on statistical data.PIN-UP Partners
What design approaches are considered outdated in slot design?
One of the outdated approaches is excessive use of special effects. Abundant animations can be irritating. Not every player is willing to waste time waiting for winnings while watching special effects. For such players, significant symbol animations are only appropriate in case of a win.MostBet Partners.
You are absolutely right. Different slot designs cater to different audiences, and adhering to a single approach would mean losing a part of the audience. The more diverse the game portfolio, the better.PIN-UP Partners.
Top 3 Mistakes in Creating Slot Design for Casinos
Lack of understanding of the slot mechanics and what exactly attracts players to slots. Before creating your design, it is essential to play various slots and take note of what aspects appeal to players in different games.
Experimenting with the core components of slots. For instance, the reels should move from top to bottom, and elements should blur when in motion. This foundation is not recommended to be altered to avoid confusing users and alienating conservative players.
Using overly bright background that distracts players from the main elements. Symbols should stand out and attract attention, and there should be a clear hierarchy in the value of symbols, so players can easily grasp which elements are more valuable and which ones are less.MostBet Partners.
Creating classic slots with the aim of appealing to a broad audience
Not keeping track of trends. For example, it's essential to stay updated and know that crash games are currently very popular in India.
Overcomplicating or oversimplifying mechanics and design elements. A slot that is too simple will quickly become boring for the player, while one that is too complex might push them away and fail to capture their attention.PIN-UP Partners.
In most gambling platforms, slots tend to be quite similar: filled with glimmering animations, spinning reels, and numerous distracting elements. Is there any point in using a fundamentally different design? If so, what alternatives are there?
In reality, it's all a bit more complex than it may seem at first glance. If you look at the most popular slots, you can see that they are qualitatively distinct. For instance, there is a specific color gradation based on human psychology, ranging from the cheapest to the most valuable. There is also a gradation in stylistics and complexity of slot elements, from smaller to larger wins. Developing slot design is both a science and an art :)MostBet Partners.
Slots are slots, and it's challenging to come up with something fundamentally new here. It makes sense to focus not on the slot itself but on the consequences of winning: jackpot animations, spinning numbers, BIG WIN labels, etc. This conveys to the player the possibility of easy money without drawing attention to the essence of the game and avoiding thoughts about the possibility of losing.
Currently, there are few new creative designs with bright slots on the market. This means that testing new approaches in creatives is definitely worth it: it can improve conversion rates and reduce banner blindness among the target audience.PIN-UP Partners.
Conclusion
One must give credit to slot designers. Usually, marketers and those looking to sell services focus on pushing the user to make a decision, concentrate their attention on an offer, a product, etc. In online casinos, they have done the exact opposite, and now you know what techniques will make the player press "spin" again and again.