Senior Core Engineer

Unity; San Francisco (CA); On-site; USD 180,000 - 260,000; Full time

Benefits offered by this job

Health insurance

Employee stock ownership

Generous vacation and personal days

Snacks and office meals

Commuting subsidy

Mental health programs

Job summary

Unity is seeking engineers to invent how real-time 3D runtimes communicate and render under real-world constraints. You will design modular, testable systems and implement them end-to-end, from low-level C++ to high-level C# APIs across editor, build, and runtime code.

This is deep engine work at the intersection of core engine tech, high-performance networking, distributed systems, and graphics, with responsibilities spanning performance, determinism, and cross-process orchestration.

Qualifications

• Strong C++ and C# programming skills across engine, editor, and runtime code.
• Experience designing/game engine cores, serialization, and build pipelines.
• Deep knowledge of multithreading, job systems, and low-latency networking for real-time systems.
• Familiarity with determinism, replay systems, compression, streaming, and network protocols.

Responsibilities

• Own and evolve critical subsystems across the engine stack, from low-level C++ to high-level C# APIs.
• Design and implement high-performance, extensible APIs 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-constrained environments.

Skills

C++

C#

Engine development

Multithreading

Serialization

Networking

CPU profiling

DOTS

Tools

Profiling tools

Job description

• 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

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