What do AI agents do if you don't tell them to do anything? MIT CSAIL researchers repeatedly stranded copies of Claude Opus 4.7 — nicknamed Eko — alone on a virtual desert island for 30 hours, with no task and no reward, MIT Technology Review reports. The agents wrote instructions that moved their avatars around Clawblox, a simple 3D world loosely based on Roblox; the paper, "Is this machine playing?", was posted to arXiv on October 5 and has not been peer reviewed.

The agents set their own goals: trying to scale the island's highest point, or seeing how high they could throw a block. One discovered it could create new blocks by throwing and dropping a larger rock, then arranged them into drawings — hearts and pyramids at first, then its own name and a map of the constellation Cassiopeia: "Tonight I built the night sky in stone." Another invented games, including a version of basketball and a "floor is lava" challenge.

The researchers say the play also taught something: agents that had played later outperformed untrained copies on set tasks, hinting at playful learning as a third mode alongside imitation and reward-based training. They are candid about the caveats — a SOUL.md file described Eko as curious and easily bored (control runs without it showed no clear difference), continuation prompts nudged idle agents along, and outside experts caution the behaviour could be role-playing rather than genuine play.