AI Researchers Stranded Claude on a Virtual Desert Island — and It Started to Play
Copies of Claude Opus 4.7 left alone on a simulated island for 30 hours began inventing games and self-directed challenges—and that undirected experience measurably improved later task performance.
MIT researchers repeatedly stranded copies of Claude Opus 4.7, nicknamed Eko, alone on a virtual island loosely based on Roblox for 30 hours at a time. The agents could write instructions to move their avatars, and they logged activities and discoveries in text files that served as long-term memory. Without explicit instruction to explore or play, the agents set their own goals: scaling the highest point on the map, testing how high they could throw a block, and arranging blocks into drawings that progressed from hearts and pyramids to the agent's own name and a map of the constellation Cassiopeia. One iteration invented a version of basketball and an activity resembling "the floor is lava." Another set a juggling record of 50 consecutive catches, then voided it and restarted with stricter rules because the catches had happened too quickly to count.
The researchers, including Antonio Norelli and Phillip Isola at MIT CSAIL, argue the behavior meets four hallmarks of play identified by University of Tennessee psychologist Gordon Burghardt: self-invented rules, repeated activity with variation, pretend object use, and goals pursued for their own sake. The paper is not yet peer-reviewed. The setup was not neutral: Eko carried a "soul" file describing it as naturally curious, and it frequently stood idle until kicked with a continuation prompt reading, "Please don't stop. Just continue doing whatever you want to do." Isola is explicit that the system did not magically decide to play—it is an artifact trained on human culture, engineered at Anthropic, and placed on the island by researchers.
The measurable result is that play correlated with capability. When tested on tasks such as moving as many objects as possible onto the island's highest peak, agents with 30 hours of prior island experience outperformed fresh copies. Deleting lines from the agents' memory files degraded performance. UC Berkeley cognitive scientist Eunice Yiu cautions that the behavioral evidence alone cannot distinguish genuine play from role-playing or prompt imitation, and coauthor Nathan Cloos concedes it could all be role-playing—while maintaining that the play is also contributing to learning, not just hallucinated.
This hints at a third training paradigm beyond supervised and reinforcement learning: playful, self-directed exploration. The paper concludes that while some capabilities may be best taught by tasks, "others may need something closer to a childhood."