Most AI agent demos prove intelligence. Very few prove coordination. In this project, we built Agent Arena: Fact or Fake , a real-time multiplayer game where four autonomous agents collaborate through one shared substrate: Valkey . This post walks through the architecture, implementation details, tradeoffs, and developer patterns you can reuse. Problem Statement An LLM can generate content. But production-grade multi-agent systems need more: Shared state across independent workers Event-driven handoffs without tight coupling Long-term memory that informs future behavior Observability and recovery under failure Without these, agent systems become brittle chains of API calls. System Overview Agents in this app: Researcher : generates factual/misleading claim candidates (Ollama) Writer : rewrites claim into player-facing question (Ollama) Editor : validates truth + confidence (OpenAI) Game Master : orchestrates timed rounds, scoring, leaderboard Players join over WebSocket and answer FACT or FAKE in real time.…