Make me a single HTML file of a rainbow slinky going down an up-escalator forever. No libraries, just canvas and code. The slinky should be a chain of springs, each coil a different color of the rainbow. It starts folded in half like a horseshoe draped over a step. When dropped it flips end-over-end down the steps and because the escalator keeps moving up it tumbles in place and never reaches the bottom. Include a drop button and a reset button.
Make it yours. Swap the object and the trick ("a rainbow slinky going down an up-escalator forever") for your own physics puzzle, and keep "No libraries, just canvas and code" and the button line for a self-contained test. A commenter suggested a speed slider, which the creator said they should ask for.
Rainbow slinky down an endless escalator
A 20-second side-by-side of a rainbow slinky flipping down an up-escalator so that it never reaches the bottom, drawn on an HTML canvas by GPT-6 Astra (left) and Claude Fable 5.1 (right) from the same prompt. Fable's run used a full 5-hour window.
“Overall I'd say Claude wins on quality and GPT wins on speed.”
How it was made
Both models ran at max. Per the creator, GPT-6 Astra was fast, while Claude Fable 5.1 errored out once it crossed the output token limit, and the creator asked it to continue after its usage ran out. The creator found Fable's more realistic and noted that Astra's slinky passes through itself. The prompt is open-ended on purpose. Inspired by the "pelican riding a bicycle" test.
Claude Fable 5.1 used the entire 5-hour window and more (the creator says about 150% of their usage); GPT-6 Astra used little of the weekly quota
Posted Sep 5, 2026 · r/singularity on Reddit · 257 upvotes · 101 comments
Prompt from: Post body, in a code block
Look notesby Reference
Two browser canvases side by side: GPT-6 Astra's light, isometric escalator with a small rainbow slinky, and Claude Fable 5.1's dark, close-up escalator where a larger slinky arcs over the steps.
- Color
- Left: a pale grey-blue page, a slate escalator, and a blue button. Right: deep navy with charcoal steps edged in yellow. Both slinkies run the full rainbow from red to violet.
- Type
- Small sans-serif interface text: the panel labels GPT-6 Astra (max) and Claude Fable-5.1 (max), a Down, forever. heading on the left, and a Rainbow slinky — up-escalator panel with buttons on the right.
- Framing
- A 16:9 frame split into two rounded panels on a dark background. The left shows the whole escalator on a diagonal in isometric view, with controls centered below; the right frames a few steps close up at a steep diagonal, with controls in the top corners.
- Structure
- The same two views throughout. Across the frames each slinky changes shape (upright, arched, folded over a step) while staying near the same spot on its escalator.
