KNEELER

KNEELER puts you on the strangest seat in motorsport: a classic F2 racing sidecar — two wheels in line, a flat platform bolted on the left, a kneeling driver, and a passenger whose entire job is to be somewhere else before the next corner arrives. 2.98 km of closed public roads, point to point, against the clock: cottages, drystone walls a metre off your elbow, a humpback bridge that puts all three wheels in the air, and eight named corners ending at the finish gantry.

The twist

The outfit cannot lean. It is a rigid tricycle with its weight hung out to one side, so the only movable ballast aboard is the 70 kg passenger — the monkey — and you drive both of them.

• Left-handers throw the load onto the outside and the chair wheel goes light. Tucked up, it lifts at about 1.15 g; past the balance point the whole machine goes over. Send the monkey out left, flat on the chair, and it stays down — or ride the lift deliberately, because a little flying is fast and it looks glorious.
• Right-handers pile everything onto the chair and unload the drive wheel — open the throttle and the back steps out. Hang the monkey right, over the rear tyre, for grip.
• Straights: let go and the monkey folds into the tuck. Worth real speed — 186 km/h tucked against 170 hung out.

None of it is scripted. Three contact patches, per-wheel loads from a rigid body at a fixed 1/120 s step, slip-based combined-grip tyres, sprung suspension, and a chair-lift bifurcation that decides — from gravity moment against cornering moment, with the monkey's mass on whichever side you put it — whether the chair settles back or takes you over.

How to play

Four things: W/↑ throttle, S/↓ brake, A/D or ←/→ steer, Q/E monkey out left onto the chair / out right over the rear wheel. The traverse takes about seven tenths of a second, so ask early. Press H or ? any time for the full controls; touch controls on phones. Crash, flip, or fling your passenger into a hedge and the run is over — R restarts instantly.

Medal times were measured, not guessed — a tuning autopilot drives the same physics through the same integrator and laps in 1:27.27: gold 1:33 · silver 1:53 · bronze 2:24. Ascending leaderboard by run time, five badges, one hidden.

How it was made

Built this run by a Claude agent team: concept and words by Fable, the simulation and world by an Opus subagent, then verified in a real headless browser — which caught what the physics harness alone could not. A sidecar's thrust line misses its combined centre of mass, so a full-throttle launch quietly steered itself into the left wall until the fix went in: a steering trim scaled by the traction actually being delivered, the same standing opposite-lock a real sidecar driver holds without thinking about it. The gearbox was also caught reading its spinning wheel as road speed and shifting to 4th at 23 km/h. Both are the kind of bug you only meet by actually driving.