Start with the right workspace
Open your preferred coding assistant or 3D tool. Use the model shown on the example as a starting point, and check any linked project for setup instructions.
GPT-6 AstraReference brief
Autonomous Model Railway With Collision Avoidance
A self-running model railway simulation with at least three trains on shared tracks. Trains autonomously operate junctions and signals to prevent collisions, with all visual design decisions left to the model. The author states this exact prompt was given to both Fable 5.1 and GPT-6 Astra.
About this example
A starting brief based on the creator's public project, not a verbatim original prompt. Your result will vary.
Creator notes
Create a self-contained HTML model-railway simulation. Include a shared track layout with junctions, signals, and at least three concurrently operating trains. Implement autonomous block-style routing: trains must switch tracks and stop at signals when their path is occupied so that collisions never occur. Make all choices for the layout, setting, visual style, colors, mood, environment, camera, detail level, and additional polish yourself. Start automatically on load with no user interaction or clicks, avoid external models, images, sounds, and asset URLs, and ensure smooth operation without console errors. A JavaScript library loaded from a CDN is permitted.
model railwaytrain simulationrailway signalstrack junctionscollision avoidanceautonomous trains3D simulationself-contained HTML
The prompt
Build a model railway with at least three trains running at the same time on a shared track layout that includes junctions and signals. The trains must switch tracks and stop at signals on their own so they never collide, without any input from the user. The layout, the setting, and the look of everything are up to you. Everything about the design is your decision: style, colors, mood, environment, camera, level of detail, and any extra touches. Do not ask me any questions, make every choice yourself and build the most impressive version you can in a single attempt. Technical requirements: one single self-contained HTML file, no external models, images, sounds, or asset URLs of any kind (a JavaScript library from a CDN is fine). It must start running on its own the moment it loads, with no clicks needed, and run smoothly with no console errors.
How to use this prompt
Choose one thing to change
Swap the subject, art style or setting. Keep the camera and interaction clear. Build a small version first, then refine one detail at a time.
Give the scene its own assets
For a custom character or prop, create a 3D model from a short object description or reference image, then bring it into your project.
Previews belong to their respective creators. Check the original source and project license before reusing code or assets.
