Game-Engine Architecture (engine-agnostic)

Game-engine architecture, engine-agnostic: the game loop (fixed vs variable timestep), ECS vs scene-graph/OOP, the render pipeline, core subsystems (physics, audio, animation, assets, memory), and netcode models. Architect- level, beyond any specific engine. USE WHEN: designing/evaluating a game engine or game's architecture in general, "game loop", "ECS", "entity component system", "render pipeline", "forward vs deferred", "rollback netcode", "lockstep", custom engine vs off-the-shelf, data-oriented game design. DO NOT USE FOR: Unity-specific work (use the `gamedev/unity-*` skills); low-level cache/SIMD detail (use `hardware-aware-design`); web graphics (use graphics s…