Senior Mobile Client Engineer — Unity/C# Expert

Scopely; Barcelona; On-site; EUR 70,000 - 100,000; Full time

Job summary

Scopely is seeking a Senior Client Engineer to join the Stumble Guys team in Barcelona. You will help design and ship production-grade mobile experiences that reach millions of players worldwide and keep Scopely at the forefront of mobile games.

You will drive game mechanics and system features using Unity and C#, ensure technical performance (crashes, FPS, startup times), and collaborate with design, product, marketing, and backend teams to deliver engaging experiences at scale.

Qualifications

• Must have strong knowledge of C# and/or C++ and game programming languages.
• Extensive experience with game engines, especially Unity or Unreal.
• Familiarity with Photon Quantum is a plus.
• Strong fundamentals in software engineering: design patterns, architecture, robust APIs.
• Solid understanding of mobile networking practices and performance.
• Experience with asynchronous, multi-threaded programming for UI responsiveness.
• Experience in client-side testing (unit/integration).
• Knowledge of game programming patterns and scalable architectures.
• Strong mobile debugging skills (iOS/Android).
• Experience with build tooling (Git, Jenkins).

Responsibilities

• Ship production-grade mobile games used by millions.
• Drive implementation of game mechanics and systems using Unity and C#.
• Develop large, complex new features and improvements.
• Ensure performance metrics (crash rates, FPS, startup times, CPU usage) stay healthy.
• Collaborate with game design, product, marketing and other teams.
• Propose solutions to challenging game development problems.
• Ensure code quality and maintainability across systems.
• Support testing and debugging across mobile platforms.

Skills

C# / C++

Unity

Photon Quantum

Mobile development

Asynchronous programming

Testing (unit/integration)

Game architecture

Performance optimization

Debugging mobile devices

UI responsiveness

Tools

Git

Jenkins

CI/CD tooling

Job description

Scopely is seeking a Senior Client Engineer to join the Stumble Guys team in Barcelona. You will help design and ship production-grade mobile experiences that reach millions of players worldwide and keep Scopely at the forefront of mobile games.

You will drive game mechanics and system features using Unity and C#, ensure technical performance (crashes, FPS, startup times), and collaborate with design, product, marketing, and backend teams to deliver engaging experiences at scale.