World Builders
Browser-based generators and simulators. Everything runs locally in your browser; nothing is uploaded.
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Claude Fable 5.1
Region Map Maker
Fantasy region and continent maps for tabletop campaigns. Set land, mountains, hills, islands, forests, deserts and swamps as percentages; parchment or realistic style; high-res PNG export.
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Claude Fable 5.1
Procedural Planet Simulator
Seeded plate tectonics over up to 4 billion years. Globe and Mercator views, timeline scrubbing, geology inspector, map export.
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GPT-6 Astra
Terra — Planet Simulator
An independent build of the same planet-simulator prompt by a different AI agent. Compare approaches and results.
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Source prompt
Planet Simulator Build Prompt
The one-shot specification both planet simulators were built from.