X-FLOW is a mobile game development company established in 2018. We gained recognition after the release of Happy Color, the most popular digital coloring book and one of the most successful ad-driven mobile apps in the world. We take pride in our diverse and talented team and partners, spread across the UK, Cyprus, the Netherlands, and other regions worldwide.
Happy Color is the largest mobile application in its category, with tens of millions of monthly active users.
We are developing a live product with a massive audience, high technical load, and a substantial UI footprint.
We’re looking for a strong Unity developer who is confident working with UI-heavy client-server applications and wants to influence product quality and architecture.
What You Will Do:
- Develop and improve client-side features.
- Collaborate with Backend, Design, QA, Analytics, and Marketing teams.
- Integrate and update third-party SDKs (ads, analytics, social).
- Investigate and resolve crashes, ANRs, and performance issues.
- Maintain build stability, asset cleanliness, and UI quality.
- Participate in designing and improving the client’s technical architecture.
Why This Role Is Interesting:
- A product used by millions of people every day.
- Real technical challenges: low-end optimization, large server-driven content catalogs, CDN pipelines, and async resource loading.
- A chance to influence client architecture - we value engineering insight and initiative.
- A low-bureaucracy environment with quick decision-making and respect for developers.
- A mature project that continues to grow and deliver stable results.
Requirements (Must-Have):
- 5+ years of commercial development experience.
- Experience working on live products with a large user base.
- 2+ years of mobile Unity development in production.
- Strong experience with UI-heavy client-server applications.
- Experience integrating ad and analytics SDKs.
- Async data/content loading and CDN workflows.
- Optimization for low-end devices.
- Strong task decomposition and deadline management skills.
- Ability to work with legacy code and follow established architectural principles.
Nice to Have:
- Mobile development experience (native or cross-platform).
- Backend experience or understanding of server-side logic.
- Knowledge of UI architectural patterns (MVC/MVP/MVVM).
- Experience with UniTask, UniRx, DOTween.
- Basic shader knowledge and rendering optimization.
Relevant Experience:
We consider the following types of projects highly relevant:
- Large server-driven content catalogs.
- Asynchronous loading of images/resources.
- Deep ad and analytics integrations.
- Pixel-perfect UI and stability on low-end devices.
Tech Stack:
Unity 2022.3, UniTask, UniRx, DOTween, Firebase, Adjust, Facebook SDK, SQLite, Git, Jira, Confluence, Slack.
What We Offer:
- Competitive salary and benefits package.
- Opportunity to work with a talented and passionate team in a creative and dynamic environment.
- Flexible working hours and remote/office work options.
- Career growth and professional development opportunities.
- A fun and inclusive company culture that celebrates diversity and creativity.
Join us and let’s create great content together!
When you apply for this role, we process your personal data in accordance with our Candidate Privacy Notice (https://xflowgames.com/candidate-privacy-notice).
