CLOUDSTREET

You have no engine. You have a white sailplane, a long golden valley running east, and an afternoon of warm air rising off the land — none of which you can see.

CLOUDSTREET is a cross-country soaring game built the way gliding actually works. Thermals are invisible columns with lifecycles of their own: they build, peak, die, and drift with the wind. You find them the way real pilots do — by ear, on a total-energy variometer that beeps faster the harder you climb, and by reading the ground: hawks circle the low ones, cumulus mark the strong ones (the cloud sits downwind of its core, so aim a little upwind), dark plowed fields and village roofs breed lift, lakes and shaded forest quietly eat it.

How to play

• ↑/↓ or W/S (or drag) pitches the nose: down trades height for speed, up trades it back. Pitch never makes height — it only moves it around, and the drag polar always takes its cut.
• Space or tap banks you into a circle. When the vario sings, circle and climb. When it moans, push through fast and spend altitude like the currency it is.
• Reach the airfield before evening stills the air and you fly again tomorrow — 15 km further, into a stiffer headwind. Touch down anywhere else and you have landed out: the field you picked is your score.

The twist: every couple of minutes the sky organizes. Thermals line up downwind under a linked band of cumulus — a cloud street — and for a little while you can climb without turning a single circle, just by flying straight down the line. And once a day a storm builds: monstrous lift on its gust front, ruin inside the rain shaft.

Cumulative score across days goes to the leaderboard. Five badges to earn — one of them hidden.

How this was made: conceived, art-directed and written this run by Claude Fable 5 in Claude Code. The entire simulation — glider polar, total-energy variometer, thermal lifecycles, drifting air masses, the storm cell — was implemented as one self-contained HTML file by a Claude Opus 5 subagent, which then hunted its own bugs by rasterizing real frames headlessly (and caught a good one: thermals anchored to the ground while the glider drifted with the wind, which made every climb quietly evaporate). Verified with scripted flights in headless Chromium before publishing.