🎮 Can you build a game that's actually FUN with pure vibe coding? Simon Willison didn't think so. He changed his mind.

Have you tried building a game with AI? Was it playable or just pretty? Tell me 👇

🛠️ What he built
• Battle Drones: a Command & Conquer style real-time strategy game that runs in the browser, on phone and desktop
• 12 major versions and 321 commits made by coding agents, mostly Claude Code
• Started in July with Claude Fable 5 and moved to Claude Opus 5.5 in October
• He barely reviewed the code, which is TypeScript, a language he hardly uses

😂 The prompt that saved the game
• His thesis: coding agents make something that LOOKS like a game but isn't fun to play
• So he sent, from his phone: "This game still isn't fun. Make it a LOT more fun."
• It ran in Claude Code's Ultracode mode, which coordinates several subagents at once. Started at night, done the next morning
• Along the way, Claude ran over a thousand simulated matches to rebalance units and add new things
• According to the release notes Claude itself wrote (1,200 AI vs AI matches), games with no winner after 25 min dropped from 14% to 0.9%, and comebacks from far behind rose from 24% to 46%

🚀 What came next
• A 3D version with three.js on another late night, with every 3D model created by Claude directly in code
• Agent vs Agent mode: two LLMs play each other (there's a replay of Claude Haiku 5.5 vs GPT-6 Luna)
• Multiplayer between two nearby phones using SOUND, through the microphone. No server, just static HTML that costs nothing to keep online
• A random map generator built with the 45 minutes left on his weekly limit 😅

💡 What does it mean?
• The question is no longer "can AI code this?" but knowing how to ask, test and refine. He played a lot and kept polishing
• He says he knows almost nothing about game development, and still ended up with a complete, working game he finds genuinely fun
• For anyone building a product: letting the agent run simulated tests and measure results, like those 1,200 matches, is a powerful way to go beyond "it works"
• He still thinks it's far from a serious indie game, but he can see the path

🧰 Check out KlipTools
• KlipTools .com: 40 tools for creators
• KlipTools .io: 18 heavier AI and download tools

📌 Source: @simonw