Scramble Yard — an AI-built endless runner (Claude Opus 5.5)

Claude Opus 5.5 built this endless runner from a single prompt. This is the real, unedited first result: no human fixes.

Kit Comet flees the Grumbleguard through a changing freight yard. Use ramps onto train roofs, collect coins, chain five power-ups and chase your saved best score through a day-to-night palette.

How to play

1. Press Run game below, then click RUN! or press Enter or Space.
2. Switch lanes with Left/Right or A/D to dodge trains.
3. Jump low barriers with Up, W or Space; roll with Down or S (in the air it fast-drops you).
4. Use ramps to get onto train roofs, collect coins and chain power-ups for a higher score.
5. On a touch screen, swipe instead. Press P or Esc to pause and M to mute.

Controls

Click RUN! or press Enter/Space · Left/Right or A/D change lane · Up/W/Space jump · Down/S roll (fast-drop in the air) · swipe on touch screens · P or Esc pause · M mute.

Browser and device

• Desktop: works with the keyboard in a current Chrome, Edge, Firefox or Safari.
• Phones and tablets: swipe controls are built in, so touch play is supported; the game has not been tested on every device.
• Needs: WebGL.
• Audio starts after your first tap or key press; M mutes.
• Use the fullscreen button for the largest view.

How it was made

• Model: Claude Opus 5.5 (Claude Code), extra-high effort
• Build time: 63m 38s, one run, first result only
• Cost: $16.82 API-equivalent (flat plan, not what was paid)
• Fresh folder, no internet, three.js provided

Its rival, Quayshift, was built by GPT-6.1 Sol from the same prompt. Play both and decide which you prefer.

Watch the head-to-head

Watch the full build comparison on YouTube (AI model vs AI model, same prompt, endless runner builds).

Get the source code and guide

Want to see how it works and remix it? Scramble Yard: AI-Built Source + Guide on Gumroad has the untouched game source, the exact prompt, build stats and a 9-page guide with three remix exercises. Or get all four games' source and guides in one bundle. No purchase is needed to play.

Licence and price

Free to play; pay what you want if you enjoy it. Original names and procedural visuals with generated sound. three.js is included under its MIT licence. Your best score is stored in your browser at this page's address, so clearing site data can remove it.

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