Senior Backend Engineer (Golang) - Castle Busters

ABOUT the company

The company is a consumer tech company founded in Paris in 2013, with one mission: entertain the world. Today we are 1,000 people, generating $1b+ in annual revenue, profitably. Our games and apps have passed 7 billion downloads and reach 200 million+ active users every month, making the company the #3 mobile publisher worldwide in downloads, after Google and Meta. We were backed by Goldman Sachs, Tencent and GBL along the way.

This position is ideally Paris-based.

TEAM

For this position, you will be an integral part of a newly established internal studio, a dynamic and focused team dedicated to one of our most promising prototype in scale. This studio is specifically chartered to improve this high-potential game up to the successful and market-ready title it is meant to become.

You will be part of the team building Castle Busters, a turn-based multiplayer game, working alongside its client engineers and game designers as a full member of the game team. You will be part of a small group owning the backend that this game needs as its requirements become more specific and demanding.

You’ll also be plugged into the company's shared gaming backend platform - the same architecture and patterns that power titles like Mob Control and Block Jam 3D - building on it and contributing back, in close collaboration with the wider backend team. You get the focus and ownership of a dedicated game engineer with the leverage and support of a battle-tested platform behind you.

This is a pivotal hire: Castle Busters is moving towards competitive multiplayer, which means moving game logic from the client to the server. You will be central to that transition.

ROLE

You will design and build the server-side foundation that takes Castle Busters from a client-authoritative game to a competitive, server-validated one. The current game computes everything on the device - progression, economy, and match outcomes alike, which won't hold up for competitive PvP. Your job is to change that.

Working closely with client developers and game designers from feature design through delivery, validation and iteration, you will:

• Build server-side validation for the metagame - currency, card upgrades, chest opens, and progression - staged by risk, replicating economy and reward logic on the server.

• Move toward server authority for competitive features, where game state lives in one place and can be trusted.

• Design APIs and player-state management that the Unity client integrates against, and help shape how client and server split responsibilities.

The responsibilities are cross-functional, ranging from infrastructure, API design & coding all the way to client-side integration (we are using Golang).

To succeed in this role, you will need to have passion for everything you do. You love to write code that scales to millions of users, are skilled at requirements gathering, champion new tech initiatives & leverage existing solutions.

PROFILE

• 7+ years of backend development experience

• Strong knowledge of computer science fundamentals

• Extreme fluency in Golang (At least 1 year in a professional environment)

• Mastery of SQL and NoSQL

• Background in high-scale systems

• Understanding of Unix-like environments

• AI-first mindset: Comfortable using AI daily and building custom agents or reusable automations to speed up your work

• Experience working in cross-functional agile teams

• Strong analytical skills with a track record of solving complex problems related to scalability, performance, and integration in high-stakes environments.

• Excellent interpersonal and communication skills, capable of influencing teams and interfacing effectively with various stakeholders.

• Ability to be self sufficient and work autonomously.

• A deep interest in game development is a plus.

BENEFITS

• Best-in-class compensation

• Other benefits according to the country you reside