Claude agents left alone on virtual island start to 'play'

Researchers repeatedly stranded copies of Claude Opus 4.7, nicknamed Eko, alone on a virtual desert island for 30 hours with no instructions. The agents' unprompted behavior resembled play.

Why it matters: Most agent evaluations measure task completion; this probes what models do with no goal, a gap relevant to long-running autonomous deployments. Unprompted behavior over many hours may reveal drift or preferences that task benchmarks miss, which matters for safety and monitoring of persistent agents.