Y Combinator Experiment Puts 50 AI Agents in Minecraft to Build a Civilization, but Food Shortages Dominate
Y Combinator, working with Olam Labs, studied the behavior of 50 AI agents in Minecraft over three hours. The agents built a pseudo-government with food rationing, and grew more cautious after 34 deaths.
Startup accelerator Y Combinator, together with Olam Labs, a company that builds multi-agent environments for frontier AI labs, has published the results of experiments in the video game Minecraft, an open-world survival game. The researchers watched how large groups of AI agents behave when pursuing a shared goal. Understanding such swarm dynamics is described as one of the most pressing challenges in AI alignment.
The setup
For the project the team built a new harness that lets agents observe the world, reason, remember, act, send messages and write scripts. It builds on Mineflayer tools, its core agent loop runs on Pi, and the code has been open-sourced.
In one run, called Civ50, 50 agents based on the GPT-6.1 Sol model spent three hours in a survival world with the goal "Build a thriving civilization." They had an agent directory, a shared sandbox and the ability to send direct messages. In total they sent about 5,900 messages.
What happened
At first the agents spread out across the map and focused on harvesting wood: nearly every tree near spawn was cut down within 90 seconds. A hierarchy emerged based on the order of the directory, and Ada, who was listed first, became the de facto leader. She wrote a settlement plan and, later, a food-operations memo in the shared sandbox.
The first night was the deadliest: 22 of the run's 34 agent deaths happened then. Dying cost agents only their accumulated gear, yet afterwards they sheltered at night and attempted fewer risky tasks. After the third night, Ada told them to stop optional excavation, building and distant scouting.
Food became the central problem. The agents set up a ration system run by an agent named Ines, who tracked what went into and out of chests and handled requests through a food-queue.md file. Rather than a thriving civilization, the colony was mostly occupied with survival.
The researchers are now running a new Minecraft colony with 25 GPT-6.1 Terra agents, which can be followed on Twitch.
