The 3 Layers Every Online Multiplayer Game Runs On

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 - Intro

0:17 - The 3 Layers of Multiplayer Tech

4:56 - Photon’s Products Across the Stack

6:54 - Transport Layers & Steam Relay Limitations

8:02 - Fusion vs Quantum + Designing for the Envelope

10:36 - Start from the Top: When Transport‑Only Makes Sense (MMOs, Server Logic)

15:53 - From PUN to Modern Netcode + Notable Games

21:21 - State Replication vs Determinism Explained

24:49 - Why Shooters Prefer Client‑Server (Lag Comp, Interest Mgmt)

26:11 - Server Build, Shared Mode, and Architecture Clarified

28:04 - Anti‑Cheat in Quantum: Replays, Spectators, Server Sim

31:49 - Grow Gradually: From Zero Servers to Full Validation

34:38 - Under the Hood: Predict‑Rollback, Physics, ECS, AI

38:32 - No Ring Buffer: Constant‑Time Rollbacks

45:28 - Testing Online, Tooling, and Community

46:15 - When to Use Fusion Instead of Quantum

50:29 - Performance: Verified vs Predicted, Clamps & Culling

52:34 - Bots, Matchmaking Math, and AI Costs

56:49 - AI Design: Verified‑Only Planning + Operational Prediction

58:02 - Verified‑Only Code Paths & Performance Targets

01:01:48 - Time Slicing AI for Stability

01:02:52 - RTS in Quantum: Flow Fields, Culling, and Use Cases

01:09:19 - Lockstep vs Prediction: Why He Avoids Lockstep

01:12:04 - Handling Rollback Spikes with Scheduling Tricks

01:13:05 - Auto‑Battlers: Verified‑Only + Snapshot Interpolation

01:15:29 - Hidden Info & Simultaneous Decisions; Server‑Gated Commands

01:21:35 - Using Quantum Offline? Licensing & Terms

01:25:03 - Determinism, ECS, and Quantum’s Hybrid Tables

01:29:22 - Could There Be a Deterministic Engine Built on Quantum?

01:31:08 - Cross‑Engine Experiments & Engine Integrations

01:35:42 - Open Worlds: Fusion Player‑Hosted vs Quantum

01:37:10 - Quantum for Open Worlds: Voxels, Persistence, NavMesh, Procgen

01:46:08 - Where Engines Stand on Multiplayer (Unreal, Unity, Source)

01:51:32 - Pricing: Free 100 CCU and Scaling Costs

01:54:45 - Long‑Tail Costs & Keeping Servers Alive

01:57:40 - Game Preservation: LAN, Offline, and Local Servers

02:04:48 - What’s New: Fusion 2.1, Quantum 3.1, Unreal Betas

02:05:55 - First Multiplayer? Start Small and Prototype

02:08:12 - Prototyping: Quantum vs Fusion (Shared Mode)

02:10:30 - From Prototype to Production: Managing Complexity

02:14:11 - What Makes a Multiplayer Hit? Trends vs Design

02:16:29 - Fusion’s New Physics Forecasting

02:17:47 - Riding vs Making Trends (Landfall’s Streak)

02:21:02 - Dogfooding: Prototyping to Improve the Tools

02:24:26 - Closing & Thanks

My 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#Overview

My 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/G3mRDrK

For the game developers among you:

➤ Join our creative game dev community on Discord: https://discord.gg/Ye6zzfQ