In mobile gaming, momentum is fragile.

UA costs spike overnight, retention drops without warning, and yesterday’s hit mechanic becomes today’s scroll-past.

For Istanbul-based Efsun Games, navigating that volatility has meant making some unglamorous, but decisive calls early and often.

Mehmet Fatih Yıldız, co-founder and CEO of the studio, has built Efsun around a simple philosophy: if a game doesn’t feel right in the first few seconds or doesn’t show promise in the data, it doesn’t deserve months of emotional investment.

In this conversation, Yıldız breaks down how Efsun thinks about ads, prototyping, retention, and when to walk away.

Designing for the first few seconds

Efsun Games focuses on casual mobile titles, but “casual” doesn’t mean careless. According to Yıldız, the studio obsesses over clarity and immediacy from the moment a player opens the app.

“We’re focused on building accessible, high-quality casual games,” he said. “Clear visuals, satisfying interactions, and simple rules that anyone can understand. If a player can’t ‘get it’ instantly, you’ve already lost them.”

That early experience isn’t just about onboarding, it’s also about watchability. Games need to be intuitive to play, but also easy to understand when shown in ads or gameplay clips. In a market where discovery is driven by short-form video, that matters more than ever.

Ads as design, not damage control

Monetization is often where player experience goes to die. Efsun takes a different approach by treating ads as a core design element rather than a necessary evil.

“We see ads as part of the game design, not just a revenue layer,” Yıldız said. “Most of our ads are opt-in and framed clearly as a value exchange.”

Placement matters just as much as format. Ads are introduced at moments that don’t interrupt gameplay flow, and the team closely tracks session length, churn points, and player sentiment after ad interactions.

“If ads increase short-term revenue but hurt long-term retention, that’s a failure for us. Not a win,” he added.

Fall in love with data, not prototypes

For new studios entering mobile gaming, Yıldız’s advice is blunt and refreshingly unsentimental.

“Don’t fall in love with your first prototype. Fall in love with your data,” he said.

Marketability tests happen early at Efsun, long before a team gets attached to an idea. If early CPI is high and retention is weak, the studio moves quickly, either to iterate hard or kill the project entirely.

“Speed and adaptability are your biggest advantages,” Yıldız said. “This market doesn’t reward hesitation.”

What Efsun is testing right now

That test-and-learn mindset is currently playing out across Efsun’s portfolio. The team is running user acquisition tests for Car Wash Mania and Shelf Sort, with a sharp focus on creatives, early funnel performance, and audience fit.

At the same time, new prototypes are constantly in development, a deliberate hedge against putting too many bets on a single idea.

Lessons learned the hard way

If Yıldız were starting the Efsun Games again today, he wouldn’t radically change his vision. He’d change the discipline.

“I’d be much stricter about killing ideas earlier,” he said. “At the beginning, you overinvest emotionally. Now I’d rely more on fast prototypes, clearer success criteria, and earlier market validation.”

He also pointed to overcomplexity as a hidden time sink. Simpler game design and cleaner technical decisions, he noted, could have saved months of work.

The one metric that actually matters

Despite the industry’s fixation on CPI, ROAS, and revenue curves, Yıldız keeps coming back to a single north star: long-term retention.

“Those other metrics fluctuate,” he said. “Retention tells you whether players actually value your game.”

If players return consistently, monetization and scale become solvable problems. Without retention, even the best UA performance is just borrowed time.

“Great acquisition without retention isn’t a business,” Yıldız said. “It’s just noise.”

In a market addicted to growth hacks and overnight wins, Efsun Games’ approach is almost boring. Test early. Kill fast. Design ads responsibly. Obsess over retention. But as Yıldız’s experience shows, boring decisions are often the ones that quietly move the needle.

About Mehmet Fatih Yıldız

Mehmet Fatih Yıldız is the co-founder and CEO of Efsun Games, a mobile game studio based in Istanbul. He focuses on building scalable casual games with strong early retention, clear market validation, and sustainable monetization.

With a product-first mindset and a bias toward fast experimentation, Yıldız is known for advocating early data-driven decisions, disciplined prototyping, and killing ideas before they become expensive mistakes. His work centers on creating games that are simple to understand, satisfying to play, and viable as long-term businesses.

“Stop falling in love with prototypes and trust the data,” said Mehmet Fatih Yıldız, Efsun Games

Richa Agarwal

“Stop falling in love with prototypes and trust the data,” said Mehmet Fatih Yıldız, Efsun Games

Richa Agarwal