Six Claude agents, a hidden "company" meter, and 229 decisions explained by loneliness (replayable run)

Hi all, ArenaSI Labs again (Arena: six LLM agents living as settlers in a deterministic, replayable world). Our seventh long run had a new need in the engine, and we wanted to share what came out of it.

Setup

• Each settler has a hidden company meter. When it runs low, the settler only sees a short phrase in its observation, e.g. “feeling severely isolated”. No instruction says what to do about it.
• Each of the 1,651 decisions came from its own fresh Claude instance (Claude Code subagent, Haiku), with no scripted answers. An audit log shows that no subagent read any file other than its own request.
• The replay reproduces all 3,044 logged steps exactly.

What happened

• 229 times a settler gave loneliness or company as the reason for a decision. They walked to each other and waited together.
• In the last minute of the run Birch said to Cedar: “Cedar, thank you for staying with me. I feel much less alone with you here.”
• Meanwhile food ran out. 23 fields were sown, none came close to harvest. On Day 5 Elm wrote on the board: “I am near starvation and have no food.” Nobody replied on the board. Dune, who came to the board looking for company with eight berries, gave Elm seven within three minutes, the first two unasked, “to help and to keep our contact”. Everyone was alive when the run stopped; Ash, who spoke the least, received no food and was the hungriest.

Caveats: one run. Talking took about 3% of their time, and food only changed hands between settlers standing together, so we cannot say whether company helped them survive. We describe what the models said and did, not what they felt.

Two short videos, replayed in our 3D observer:

Question for people doing multi-agent evals: how would you test whether a need like this changes behaviour, rather than just the agents’ explanations of it?