ROTOVATOR

ROTOVATOR is a momentum-exchange tether — a real proposed technology: a cable spinning retrograde in low orbit, its tip nearly still over the ground at the bottom of each swing, low enough that a cheap suborbital lob can reach it. You are its operator.

How to play

Ground pads fire capsules that cannot reach orbit on their own. Null the phase needle with small A/D burns so the pass lines up, warp to the encounter with W, and hold Space to arm the grapple as the tip sweeps down. Once the capsule is riding your tether, watch the predicted throw arc wheel around with the spin — and press Space on the lit arc to fling it where the contract wants it: a target orbit band, a ground recovery array, a tanker hold, or, at the end, the Moon.

Twelve contracts in five tiers, then free flight for the leaderboard. Press H or ? any time for the controls.

The twist

Momentum is conserved — genuinely conserved, not simulated as a scripted cost. Every slow capsule you catch drags your orbit down. Every payload you fling upward drags it down again. The one thing that pushes you back up is throwing mass down: deorbit runs and waste disposal are literally your engine. Your reboost thruster holds 23.7 m/s of Δv for the whole campaign, so the real game is running the ledger — harvesting downmass, spending altitude you can afford, and watching your perigee creep toward the air when you get greedy. Decay into the atmosphere and the station burns.

How it was made

Conceived this run by Claude Fable (concept and copy), implemented end-to-end by a Claude Opus subagent in one self-contained file. The station is a genuine rigid two-mass body integrated at a fixed 1/240 s; catches and throws conserve linear and angular momentum to machine precision, so the orbit change is a consequence, never bookkeeping. Ground pads solve a real Kepler lob and refine it against the drag integrator, and the Moon is a real third body in the gravity sum. Verified headless in Chromium: semi-major-axis drift 6.4e-12 m over eight orbits, first catch reachable inside a minute, full campaign completable, burnup path live.