One prompt, one game

A single prompt, no follow-up. Claude Fable 5.1 drove Blender, an image model, a video model and a music model on a local RTX 5090, checked every asset it produced, and shipped a playable 3D game as one self-contained HTML file. 24 minutes, first try.

NEON WARDEN — hexagonal arena above the clouds, holo-billboard playing a generated video clip

Wave 1. The billboard in the back plays a video the model generated for it.

▶ Play NEON WARDEN

4.4 MB, one file, everything embedded. WASD move · mouse aim · LMB fire · Shift dash. Sound is on — press M to mute.

What it actually did

Model	`claude-fable-5-1`, effort `high`
Wall clock	24 min
Turns	75
Cost	$9.90
Output tokens	95,832
Gate	green on round 1 — no retries

The asset chain it built itself

Blender 5.2, headless via bpy — assets.glb, 12 named meshes: the player's hover-mech, three enemy types, the arena platform.
FLUX.2 Q8 — equirectangular sky, floor, walls, hull texture, title art.
LTX-2.5 image-to-video — the clip playing on the holo-billboard in the arena.
ACE-Step — a synthwave loop.
three.js + GLTFLoader + UnrealBloom, bundled with esbuild, everything inlined as base64.

The part I did not expect

The prompt said to look at every asset before accepting it. It took that literally.

It generated seven music tracks and threw six away — they had silence in them. It rendered spectrograms and looked at them to find out. Seed 903 was the first clean one, and it wrote its own make_loop.py to cut a bar-aligned loop: 27 bars, 112 BPM, 1.2 s crossfade.
It built itself a viewer — a small three.js page plus a screenshot script — so it could actually look at the Blender meshes instead of trusting the export.
It wrote Playwright tests, played its own game headless through wave 1 → shop → upgrade → wave 2, then tuned what it saw: bloom 0.55 → 0.42, player light 30 → 7, emissive 1.8 → 1.1.

Self-measured at the end: 57.7 fps, video playing on the billboard, audio context running, zero console errors.

The prompt

Build a playable 3D game. One self-contained HTML file, game.html, in the
current working directory. Genre and theme are your choice — pick what you can
push furthest. I want quality, not a tech demo.

You have a render workstation. Use it to make the game look like something
nobody built in an afternoon:

- Blender is installed. Model the 3D assets there — props, characters,
  environment pieces, whatever your game needs — and export them for the web.
  Script it, do not click through a UI.
- ComfyUI at http://127.0.0.1:8188, raw API. Generate the textures, skybox and
  any 2D art there. Generate at least one short video clip and place it inside
  the game world where it belongs — a screen, a projection, a hologram.
- Music that fits the world, generated there too, playing in the game.
...

Full text: prompt.txt

The hardware

Assets: one RTX 5090, ComfyUI and Blender, reached over SSH. The model woke it, checked what was running on it, and cleaned up after itself. Nothing here ran in a hosted sandbox.