Photon Quantum
This article explains Photon Quantum as a deterministic multiplayer engine for Unity built on ECS and predict/rollback networking. It covers the core mental model of separating Quantum simulation from Unity view, how input, commands, events, and signals work, how .qtn DSL, Frame, physics, KCC, and assets fit together, and why Quantum is best for fast, fair competitive games that need rollback rather than simple state sync. It also ends with practical guidance, common pitfalls, and when to choose Quantum over Fusion or PUN.