Inside Slot Design: How Just Slots Turns Sketches into Spins

Most players see only flashing reels and bonus bursts. Josué Agüero sees a storyboard, a math model, and a launch checklist. A game producer and product owner at Just Slots, Agüero walks us through how modern slots are conceived, tested, and shipped, and why the small details matter as much as the headline features.

From sketch to spin

A producer’s job touches nearly every part of a slot’s lifecycle, from first idea to day-one release. Agüero describes it this way: 

“A game producer basically is the one, the person that glues and holds everything together at the end of the day.” 

He moves between sketching mechanics, syncing with artists and animators, and working “really, really, really close” with mathematicians to balance gameplay.

In practice, that means translating inspiration into requirements the studio can execute, then shepherding build reviews, deadlines, and marketing assets until the game is ready to go live. The goal is consistent: keep the project aligned and the player experience coherent.

Where ideas begin

At Just Slots, concepts aren’t pulled from a single source. 

“We basically get some ideas that are trending. We also have our own ideas. We also collect players’ feedback as well,” Agüero says. 

Those ideas are tracked in a backlog, prioritized against a feature roadmap, and handed to the studio once a theme is locked.

Creative direction is intentionally broad at the start. Art teams will explore multiple visual routes, from familiar categories such as ancient civilizations to “something that is very unique and really crazy”, before the team lands on a look that supports the mechanic and tells a clear story.

Listen to the full interview on our Podcast:

Timelines and scope

Speed matters in a crowded market, but only if quality holds. Some games reach launch in one to two months, although scope changes can extend that. Agüero’s rule is to refine without losing momentum: if a strong idea isn’t right for this release, it moves to the backlog rather than derailing the schedule.

“Balancing the creative ambition versus what is technically feasible” is the main constraint, he says. 

Coordinating artists, developers, math, and QA requires trade-offs that preserve what players will actually feel on screen.

Making features feel fresh

Bonus rounds and free spins keep players engaged, but repetition kills interest. Agüero argues producers should be active players themselves to spot friction and delight. 

“It needs to tell a story. It needs to bring something that is unique, that basically makes the player continue spinning and enjoying the game,” he told casinos.com.

That player-first lens guides polish passes late in development. The team trims overlong animations, sharpens moments of anticipation, and ensures each feature supports the central theme rather than distracting from it.

Test days, QA, and live feedback

Pre-release, Agüero plays “from the player’s eyes,” asking whether animations “are telling the right story "And whether there is a genuine surprise moment. He partners closely with QA to focus testing on what matters for launch. Not every post-launch suggestion warrants a hotfix, but patterns inform sequels and future titles.

He also watches streamers and reads chat reactions after release. Negative notes get logged as to-dos; positive signals help the studio repeat what resonates.

Launch day: nerves and celebration

The moment a slot goes live is equal parts excitement and triage. The team prioritizes what must ship now and what can wait for the next title. 

“It’s excitement and also getting a nerve, basically, to make sure that everything is in place,” Agüero says.

A standout release

Agüero singles out Shogun Skylord as a personal milestone. 

“It has a special place in my heart… it was like my official first release, you know, where I could implement some changes and shape a little bit how we approach the development today.” 

The title has been one of the studio’s strongest for player retention, a core metric alongside turnover and behavioural analytics that track how features perform over time.

Story first, then math

Asked what would surprise players about development, Agüero points to the invisible structure behind the spins. The team builds narrative through the base game and features, then aligns the math to that arc so potential and pacing feel earned. Easter eggs sometimes make it in too; small surprises tucked into designs or animations for sharp-eyed fans.

Creativity, AI, and the next wave

AI is a tool in the pipeline, not a replacement for craft. “It doesn’t feel the same… it’s missing something at the end of the day,” Agüero says, though he expects progress. For those looking to enter the field, his advice is simple: play games, learn to love the details, and be open to feedback. 

“Have fun with the work that you’re doing… then the players will be also perceiving that.”

In Touch with the Players

Online slots reach millions of players and compete for attention in seconds. Understanding how ideas become features, and how teams measure what keeps players engaged, explains why some games stick and others fade. Studios that combine distinctive art, coherent math, and disciplined scope can ship faster without shipping forgettable.