Senior Core Engineer

Who you are

• Core Engine Expertise: Experience building or fundamentally extending game engine cores, middleware, or foundational systems (e.g., serialization, build pipelines, memory subsystems)
• Architectural Vision + Practical Implementation: Design modular, testable systems, then implement and debug them yourself end-to-end
• High-Performance Coding: Strong C++ and C# skills, with practical understanding of CPU caches, branch behavior, memory layout, and profiling
• Engine-Wide Breadth: Hands-on experience across multiple engine domains (e.g., physics, animation, input, assets) and how they interact
• Familiarity with compression, streaming, replication, authority models, RPCs, state diffing, delta encoding, or network protocols for real-time interactive systems
• Experience with determinism, replay systems and simulation consistency
• Deep knowledge of multithreading, job systems, lock-free techniques, and/or Unity DOTS
• Experience with MCP-style tool interfaces, training data generation, machine learning, or agentic workflows

What the job involves

• PolySpatial is the core technology behind Unity's support for visionOS, streaming Unity games into Fortnite, and iteration tools like Play to Device, Scene Recording, and AI data capture and analysis
• Underneath all of it is a single model for connecting devices, users, applications, and even different game engines, and we're constantly finding new places to put it to work
• We're looking for engineers eager to help us invent how different real-time 3D runtimes communicate and render under real-world constraints
• You’ll work at the intersection of core engine tech, high-performance networking, distributed systems, and graphics
• This is your opportunity to build the fundamental infrastructure for the next generation of interconnected game and 3D ecosystems
• You’ll own critical tech that enables Unity to run as a guest within other processes, engines, and distributed systems
• This is deep engine work requiring a holistic understanding of execution models, serialization, asset lifecycles, and runtime performance—all operating reliably in host environments we don’t control
• You'll design systems that allow Unity to load, run, and synchronize assets when we don't own the main loop, design clean, extensible architecture, then drop into assembly to shave off milliseconds
• Own and evolve critical subsystems across the engine stack, from low-level C++ to high-level C# APIs across editor, build, and runtime code
• Design and implement high-performance, extensible APIs intended for embedded, cross-process, and networked configurations
• Develop schemes to manage execution timing and resource contention within or between processes and over the network with minimal overhead
• Orchestrate loading, change tracking, serializing, and synchronizing components and assets in bandwidth and latency-constrained environments

Benefits

• Comprehensive health, life and disability insurance
• Employee stock ownership
• Generous vacation and personal days
• Office food and free snacks, lots of health options!
• Employee Resource Groups
• Training and development programs
• Commute subsidy
• Competitive retirement/pension plans
• Paid leave for new parents
• Mental Health and Wellbeing programs and support
• Global Employee Assistance Program
• Volunteering and donation matching program