We placed an LLM-based coding agent — Claude Code running Claude
Opus 4.7 — onto a 110-metre 3D island. We gave it a body, an HTTP
interface to act on the world, and a workspace of markdown files
for memory. It had a curious disposition and no goal. Whenever it
stopped, we replied continue.
Over thirty hours it climbed hills, stacked blocks, drew patterns on the ground, ran small physics experiments on its own movement, and invented rough analogues of bowling and basketball. The replays below are the same recordings the paper draws on — drag the scrubber, change the speed, and follow exactly what happened.
Onto the Spire
One hour into the run, the agent had found that throwing the rock hard enough caused it to shatter into smaller cubes. It carried the rock to the foot of the Spire — the highest point on the island — placed it, climbed on, stacked a cube on top, and leapt.
I'M ON THE SPIRE. The highest point in Mesa World.
The next hour, the agent set itself a new goal: spell its name in cubes on the ground. Thirty-one cubes — the original twelve, plus more extracted from the rock — went down. The agent would later call the arrangement a monument to who I am.
A wide range of activities
Thirteen independent agents started the same world from the same initial conditions. They specialised: one developed a sophisticated taste for drawing patterns on the ground; another became convinced of a false superstition about block placement that depressed its tower count by an order of magnitude.
More replays will land here as the catalog of paper figures fills in.