Benchmark snake

The test

When a new model comes out, I give it a description of a game I want: Snake, played on the surface of a sphere. Then I look at what comes back.

Any current model can write flat Snake. The sphere version is harder because a sphere has no grid and no edges, so the model has to decide what a turn means on a curved surface and where to put the camera. Until recently, what came back didn't work.

The one before this

The previous version, which I think one of the Gemini models built, was the first that felt like a game. It steered by compass: the keys meant north, south, east and west, and the camera kept north at the top of the screen.

That holds up at the equator. Near a pole, north points a different way every few steps, so the camera swung wildly, and the model had written special cases to get the snake across. That version is still here, behind the vault in the original SecureSpin.

The brief

I gave that code to Claude Fable 5.1, Anthropic's model, and told it nothing in there was fixed. I wanted its own take on the idea. I also wanted to see what it would add and how it would improve the parts it kept.

What it built

Fable threw out latitude and longitude. In this version the snake carries its own sense of "up" along the surface as it moves, and the camera rides directly above the head using the same "up". The four keys mean the four directions on your screen.

No part of the game knows where north is, so the poles are ordinary places and the camera has no reason to turn. The grid on the globe is a mesh of triangles, with no lines bunching at the top and bottom.

It kept the three speeds and the high-score table. It added a chain multiplier for eating quickly and a boost you hold for double points.

One rule comes straight from the geometry. After a U-turn, the two halves of your body drift toward each other, because parallel lines on a sphere meet. A long snake can't run beside itself for long.

How it checked its work

Fable built the game in one session. It put the movement rules in their own file, sim.js, with ten tests. One test drives the snake straight through the old north pole and another starts it there.

An autopilot plays the game behind the title screen. The tests use the same autopilot to cover the whole sphere.

The verdict

It's definitely one of the best I've seen.

Play it

Snake 3D is in the arcade. W, A, S and D or the arrow keys steer, and Space is boost.