BEAM There, Done That with Ellyse Sedeno - Why Multiplayer Games Are Just Distributed Systems

This podcast is relevant particularly for the architectural discussion around how OTP primitives map to the domain of multiplayer games.
Ellyse Sedeno has been working at the intersection of distributed systems and game backends since the early days of MMORPGs. Her starting point is that multiplayer games and telecom systems face structurally similar problems: millions of concurrent sessions, soft real-time requirements, failure isolation between subsystems, and distributed state that has to be consistent without being globally locked.
The episode covers how the traditional game server architecture - threaded Java or C++ with explicit lock management - fails under load in ways that are both predictable (deadlocks are non-deterministic and nearly impossible to reproduce) and expensive to fix after the fact.
The alternative she describes maps cleanly onto OTP:
A presence server, chat server, world server, and combat server run as separate supervised processes. Each player and mob has its own process. Movement events arrive in a mailbox, are processed without locks (there is no shared mutable state to lock), and changes are broadcast. When the world server crashes, it restarts under supervision without affecting chat. The architecture makes failure modes visible and recoverable rather than total.
One observation worth discussing from an Erlang perspective: she makes the case that the call vs cast distinction matters significantly in game server design. Circular dependencies between server processes using synchronous calls are the actor model’s equivalent of a threading deadlock - and they’re much easier to reason about structurally when your dependency graph is explicit in your process topology.
She also discusses using player behavior analytics as an observability layer - aggregate deltas in chat volume, level completion rates, and movement patterns as leading indicators of server-side failures. At scale, player behavior is a higher signal-to-noise instrument than server logs that have become too noisy to read.
The project is open source on Codeberg as game_server.