This is a Game Dev Podcast with my guest Erick Passos from Photon Engine (Exit Games Inc.), a company that provides networking solutions and server architecture for online multiplayer games. I try to understand more about how how online multiplayer works in general and in particular how to use Photon's Quantum and Fusion to develop online games faster.Links to my Guest➤ Photon Engine: https://www.photonengine.com/Listen to the podcast on the go (Spotify, Apple Podcasts, etc.):➤ https://tyrollerjonas.podbean.com/0:00 - Intro0:17 - The 3 Layers of Multiplayer Tech4:56 - Photon’s Products Across the Stack6:54 - Transport Layers & Steam Relay Limitations8:02 - Fusion vs Quantum + Designing for the Envelope10:36 - Start from the Top: When Transport‑Only Makes Sense (MMOs, Server Logic)15:53 - From PUN to Modern Netcode + Notable Games21:21 - State Replication vs Determinism Explained24:49 - Why Shooters Prefer Client‑Server (Lag Comp, Interest Mgmt)26:11 - Server Build, Shared Mode, and Architecture Clarified28:04 - Anti‑Cheat in Quantum: Replays, Spectators, Server Sim31:49 - Grow Gradually: From Zero Servers to Full Validation34:38 - Under the Hood: Predict‑Rollback, Physics, ECS, AI38:32 - No Ring Buffer: Constant‑Time Rollbacks45:28 - Testing Online, Tooling, and Community46:15 - When to Use Fusion Instead of Quantum50:29 - Performance: Verified vs Predicted, Clamps & Culling52:34 - Bots, Matchmaking Math, and AI Costs56:49 - AI Design: Verified‑Only Planning + Operational Prediction58:02 - Verified‑Only Code Paths & Performance Targets01:01:48 - Time Slicing AI for Stability01:02:52 - RTS in Quantum: Flow Fields, Culling, and Use Cases01:09:19 - Lockstep vs Prediction: Why He Avoids Lockstep01:12:04 - Handling Rollback Spikes with Scheduling Tricks01:13:05 - Auto‑Battlers: Verified‑Only + Snapshot Interpolation01:15:29 - Hidden Info & Simultaneous Decisions; Server‑Gated Commands01:21:35 - Using Quantum Offline? Licensing & Terms01:25:03 - Determinism, ECS, and Quantum’s Hybrid Tables01:29:22 - Could There Be a Deterministic Engine Built on Quantum?01:31:08 - Cross‑Engine Experiments & Engine Integrations01:35:42 - Open Worlds: Fusion Player‑Hosted vs Quantum01:37:10 - Quantum for Open Worlds: Voxels, Persistence, NavMesh, Procgen01:46:08 - Where Engines Stand on Multiplayer (Unreal, Unity, Source)01:51:32 - Pricing: Free 100 CCU and Scaling Costs01:54:45 - Long‑Tail Costs & Keeping Servers Alive01:57:40 - Game Preservation: LAN, Offline, and Local Servers02:04:48 - What’s New: Fusion 2.1, Quantum 3.1, Unreal Betas02:05:55 - First Multiplayer? Start Small and Prototype02:08:12 - Prototyping: Quantum vs Fusion (Shared Mode)02:10:30 - From Prototype to Production: Managing Complexity02:14:11 - What Makes a Multiplayer Hit? Trends vs Design02:16:29 - Fusion’s New Physics Forecasting02:17:47 - Riding vs Making Trends (Landfall’s Streak)02:21:02 - Dogfooding: Prototyping to Improve the Tools02:24:26 - Closing & ThanksMy game "Thronefall":➤ Steam: https://store.steampowered.com/app/2239150/Thronefall/➤ Discord: https://discord.gg/gVYctptyg8➤ Nintendo Switch: https://www.nintendo.com/en-gb/Games/Nintendo-Switch-download-software/Thronefall-2669627.html#OverviewMy game "Will You Snail":➤ Play Will You Snail on Steam: https://store.steampowered.com/app/1115050/Will_You_Snail/➤ Join the Will You Snail Discord: https://discord.gg/G3mRDrKFor the game developers among you:➤ Join our creative game dev community on Discord: https://discord.gg/Ye6zzfQ