Claude Fable 5.2
Duskline
3D endless runner: a maintenance robot flees a sweeper drone along an elevated metro line at sunset
- 91 KB
- 84 plays
- Endless Runner
- WebGL
- Mobile
- Single File
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About Duskline
Duskline is a 3D endless runner set on an elevated metro line above a city at sunset. You're a small maintenance robot, and a sweeper drone wants you off its tracks. Switch between three lanes, jump low barriers, slide under high ones, run up ramps onto the roofs of trains, and dodge the trains coming the other way, all while the speed keeps climbing.
Hit something once and the drone closes in. Hit something again before it backs off and it catches you.
How it's made
Claude Fable 5.2 wrote it from a single prompt that asked for no libraries, no CDNs and no assets, so the WebGL renderer is hand-written. The sunset sky with its city silhouette, the lit windows of the tower blocks, the streetlight grid far below, the trains and the robot are all generated in code, and the sounds (train horns, the drone's beeping, spark pickups) are synthesized with Web Audio. It's one 91 KB HTML file that plays on desktop or with swipes on a phone, and it lowers its quality automatically if the frame rate drops.
Credits
Made by Raúl Berná with Claude Fable 5.2.
Duskline guide & tips
The rules
- Three lanes. Move left and right, jump low barriers and slide under high ones.
- Trains come in every lane. Some are parked and some are moving toward you; a horn warns you about a moving one.
- Ramps lead up onto parked trains, and you can run along the roofs.
- First hit: "The sweeper is closing in". The drone moves right behind you for 6.5 seconds and beeps.
- Second hit before it backs off: CAUGHT, and the run is over. Once you hear "The sweeper backs off", you're safe again.
- Crashing into a train slows you right down and shoves you into a free lane. Smashing through a barrier halves your speed. Both count as a hit.
Scoring
- 1 point per metre, plus 10 per energy spark.
- Your best score is saved in the browser. The end screen shows score, sparks, distance and time.
- Speed rises throughout the run, quickly at first and then steadily, so a good run lasts about two minutes.
Power-ups
| Power-up | Effect |
|---|---|
| Magnet | Pulls nearby sparks in for 9 seconds |
| Shield | Absorbs one hit completely. The drone doesn't close in. |
Tips
- After a hit, play safe for 6.5 seconds. Stay in the open lane, skip the risky sparks, and wait for "The sweeper backs off".
- Train roofs are the safest place to be: nothing comes at you up there, and ramps are lined with sparks.
- Moving trains close the gap much faster. Change lanes as soon as you hear the horn.
- Pick up a shield whenever you can. It turns your next mistake into nothing.
- Restart is instant: Space, Enter or a tap.
Controls
| Input | Action |
|---|---|
| ← / → or A / D | Change lane |
| ↑ or W | Jump |
| ↓ or S | Slide |
| Swipe left / right / up / down | The same on touch screens |
| P or Esc | Pause |
| Space, Enter or tap | Start / run again |
How to play Duskline online
Duskline is a single self-contained HTML file (91 KB) hosted on this site. Press Play Game and it runs in an isolated sandbox. You can also download the .html file and open it offline in any modern browser, or read every line in the Inspect Source tab.
Under the hood it uses WebGL.
Controls
- Arrows or WASD
- Left/Right change lane
- Up or Space jump
- Down slide
- Swipe on touch
- P pause
- M mute
On a phone, tap Play and the game opens fullscreen with its own touch controls.
Tip: click inside the game once to capture the mouse, and press ESC to release it. Fullscreen gives the best frame rate on large monitors.
The prompt behind Duskline
The exact instruction Raúl Berná gave Claude Fable 5.2. Copy it from the View Prompt tab above.
Make a fast, fun 3D endless runner in a single HTML file, with nothing external: no libraries, no CDNs and no assets, so write the WebGL yourself. You are a small maintenance robot escaping along an elevated metro line above a city at sunset. A sweeper drone chases you. Three lanes: swipe or press left/right to change lane, up to jump, down to slide. Trains come at you in all lanes, some parked, some moving towards you; low barriers you jump, high ones you slide under. You can run on top of train roofs and reach them with ramps. Hit something once and the drone closes in; hit again before it backs off and it catches you. Collect energy sparks along the track. Two power-ups: a magnet that pulls sparks in, and a shield that absorbs one hit. Speed keeps rising, so a good run lasts about 2 minutes. Show score, sparks and best score (saved locally); restart is instant. Make it feel great: smooth lane changes, camera behind and slightly above, speed lines, screen shake on hits, satisfying sounds made with Web Audio. Works on desktop (arrow keys or WASD) and on mobile (swipes), and lowers quality automatically if the frame rate drops. All text in English.
Duskline FAQ
- How does the drone catch you in Duskline?
Your first hit makes it close in for 6.5 seconds. Hit anything else in that window and it catches you; survive it and the drone backs off again.
- How is the score calculated in Duskline?
One point per metre run, plus 10 points for every energy spark. Your best score is saved in the browser.
- Can I play Duskline on my phone?
Yes. Swipe left and right to change lanes, up to jump and down to slide. It works in portrait or landscape.
- Does Duskline use a game engine?
No. The prompt asked for no libraries, CDNs or assets, so Claude Fable 5.2 wrote the WebGL renderer, models and sound itself in a single 91 KB file.
- Is Duskline free to play?
Yes. Duskline runs in your browser for free, with no download, account or install. It is a single HTML file hosted on this site.
- Can I play Duskline on a phone or tablet?
Yes. It has its own touch controls. It works with the phone held either way.
