Principal Physics Programmer, C++ (Modeling & Simulation)

About Code Metal Code Metal is the leader in automated software engineering you can trust. As AI writes more of the world's code, the bottleneck in software has shifted from writing code to verifying it works, and AI cannot verify its own work with certainty. Code Metal takes a fundamentally different approach: constrain AI to what it does reliably, verify every step independently of the model using formal methods, and keep engineers in the loop on the decisions that matter. The result isn't code that probably works — it's code that is provably correct, with auditable proof. Customers including the U.S. Air Force, L3Harris, RTX, and Toshiba use Code Metal to modernize legacy code, optimize performance on real hardware, and move prototypes to production, fast. Founded in 2023 with offices in Boston and San Francisco, Code Metal is funded by Accel, Salesforce Ventures, B Capital, Smith Point Capital, J2 Ventures, Shield Capital, Overmatch, RTX, and others. Learn more at codemetal.ai . About the Role: Our Modeling & Simulation team is building the next-generation wargaming and decision-support platform that helps the DoW make multi-billion-dollar force-design decisions before those decisions are made in the real world. The team spans simulation and physics, backend and data systems, frontend and geospatial visualization, and AI systems, working together to turn operational questions into extensible, mission- and campaign-level simulations that government users can trust. Help redefine how the DoW makes multi-billion-dollar force-design decisions. We're looking for a Physics Programmer to bring the performance standards of commercial game development to our next-generation wargaming platform. You'll architect and build the core C++ simulation runtime that executes physics, behavior, and mission models developed by engineers and domain experts across the organization. Scope of ownership, architectural authority, and mentorship responsibility scale with level — see “Level Expectations by Track” below. Your work will span entity-component systems, data-oriented architecture, simulation scheduling, concurrency, deterministic execution, memory management, model integration, and engine-wide performance. The strongest candidates will come from commercial game development, game-engine development, or another performance-constrained real-time environment where frame time, memory, latency, stability, and hardware limitations are non-negotiable. You may have built a custom physics engine, owned core systems within a proprietary engine, or developed low-level physics and runtime infrastructure for a major game platform. Defense experience is not required. We care more about whether you have shipped real-time C++ systems, optimized them under hard performance budgets, and made foundational architectural decisions within a complex engine codebase. What You’ll Do: Architect and implement the core C++ runtime behind a large-scale, interactive wargaming platform. Own the structure, performance, and long-term health of a substantial engine codebase. Design and evolve an entity-component-system architecture for representing large numbers of heterogeneous simulation entities. Build data-oriented component storage, entity lifecycle management, system queries, execution graphs, and dependency-aware scheduling. Define the engine interfaces through which physics, AI, sensor, weapon, behavior, and environmental models are registered and executed. Create stable extension points that allow model developers to add capabilities without modifying or destabilizing the engine core. Design simulation loops, fixed and variable time stepping, event processing, system ordering, state transitions, and deterministic replay. Develop multithreaded and task-based execution systems that safely parallelize simulation workloads. Optimize memory layout, allocation, cache locality, component access, serialization, and data movement. Profile and improve CPU utilization, memory use, latency, throughput, and simulation rate against explicit performance budgets. Build spatial indexing, broad-phase query, collision-candidate, visibility, and proximity-query infrastructure. Integrate externally developed physics and mathematical models into a consistent, performant runtime. Develop checkpointing, snapshotting, state replication, save-and-restore, and reproducible replay systems. Establish clear architecture for networked and distributed simulation, including ownership, synchronization, prediction, and state transfer. Build tooling that allows model developers to inspect entities, debug system execution, profile model cost, and understand simulation state. Identify and eliminate architectural bottlenecks as simulation scale and model complexity increase. Lead engine design reviews, mentor other programmers, and raise the standard for C++ architecture and performance engineering. Remain deeply hands-on in implementation, profiling, debugging, and code review. Required Qualifications: Extensive professional C++ development experience, or equivalent experience, building performance-critical production software. Significant experience in commercial game development, game-engine development, or a similarly performance-constrained real-time environment. Experience shipping at least one commercial game, engine, platform, or interactive real-time product. Demonstrated ownership of foundational engine systems rather than primarily gameplay features, scripting, tools, or application-level integrations. Experience building or substantially extending a physics engine, game engine, simulation runtime, ECS, job system, or comparable core technology. Expert command of modern C++, including object lifetimes, ownership, templates, concurrency, synchronization, profiling, and low-level debugging. Strong understanding of data-oriented design, memory layout, cache behavior, allocation strategies, and performance-sensitive data structures. Experience designing or extending an entity-component system or comparable composition-based runtime architecture. Experience with engine loops, execution graphs, task systems, event systems, dependency management, or runtime scheduling. Demonstrated ability to optimize against hard CPU, memory, latency, and frame- or tick-time budgets. Experience using commercial profiling and debugging tools to diagnose CPU stalls, memory issues, thread contention, allocation problems, and cache inefficiencies. Working knowledge of real-time physics concepts such as coordinate systems, numerical integration, collision detection, spatial partitioning, constraints, and simulation stability. Experience designing APIs, plugin systems, SDKs, or extension frameworks used by other programmers. Experience maintaining and improving a large C++ codebase while continuing to deliver production capabilities. Experience leading major technical initiatives while remaining an active individual contributor. Active Secret clearance or eligibility to obtain one. Strongly Preferred: Experience with SIMD, GPU compute, custom allocators, job systems, lock-free structures, or platform-specific optimization. Experience supporting very large worlds or simulations containing large numbers of active entities. Experience with engine-level serialization, snapshotting, replay, world partitioning, or streaming. Familiarity with aerospace, robotics, autonomy, and defense simulations (e.g., HLA, DIS, OneSAF, JSAF, NGTS, STK, AFISM) Experience supporting Air Force, Space Force, joint, or broader DoW acquisition and mission-analysis programs. Experience developing models for sensors, weapons, electronic warfare, jamming, communications, logistics, or command and control. Active U.S. security clearance (Secret, Top Secret, or SCI/SAP). Principal Level Expectations Years of Experience: 10+ Engineering Craft & Code Quality: Sets the quality and correctness bar across the department; their work is the example others learn from; improves the automated systems and practices that ensure quality department-wide. Architecture & Technical Knowledge: Provides architectural guidance across the department and invents paradigms that solve CodeMetal-specific domain problems (e.g., translation, optimization, deployment across target environments); a key resource on every major system. Delivery, Scoping & De-risking: A consistent contributor to the company's technical roadmap; gives reliable estimates for large cross-team initiatives; ensures pragmatic scoping toward the most valuable outcomes. Technical Leadership & Mentorship: An active driver of company-wide architectural reviews and proposals; mentors mid-level and senior staff at scale; influences others across departments toward the best technical outcome. Benefits Pay depends on experience, but we strive to be at the upper end of the salary range Health care plan with 100% premium coverage, including medical, dental, and vision 401k with 5% matching Paid Time Off (uncapped vacation, plus sick and public holidays) Flexible hybrid or remote work arrangement Relocation assistance for qualifying employees Wage Transparency - The salary range for this role is not a guarantee of compensation or salary, as the final offer amount may vary based on factors including, but not limited to, individual proficiency, skills, experience, and location. We are an equal opportunity employer. US Citizenship may be required for certain project assignments involving security clearance. Pursuant to the San Francisco Fair Chance Ordinance, we will consider for employment qualified applicants with arrest and conviction records.