Battle Drones - a vibe coded RTS with audio-based multiplayer

Simon Willison describes Battle Drones, a browser-based Command & Conquer-style RTS built largely by coding agents such as Claude Code over 12 major iterations and 321 commits, with 3D models, fog of war, multiple maps and a random map generator, several game modes, and AI personalities. It supports multiplayer between two nearby devices by synchronizing game state over audio, and an online multiplayer mode was later added via a stateless WebSockets relay server on Fly.io. The post also covers agent-vs-agent battles where two LLMs play each other, and lessons such as using a deterministic simulation engine for replays and multiplayer.