Bring the rocket down for a soft, upright touchdown on the droneship — just like SpaceX. Balance five parameters at once before the fuel runs out.
This is the whole point of the game. A rocket doesn't just "come down" — at the instant of touchdown, every one of these has to be right simultaneously, or you crash:
| Parameter | What it is | Safe at touchdown |
|---|---|---|
| Descent rate | how fast you're falling | slow (gentle contact) |
| Lateral speed | sideways drift | near zero |
| Tilt angle | lean from vertical | almost upright |
| Angular rate | how fast you're spinning | almost still |
| Pad position | where you are over the deck | on the green pad |
| Fuel | budget for all the above | must not hit zero first |
And the environment fights you: a random wind pushes the booster sideways every attempt, and your starting pad offset means you must fly over to the deck while bleeding off speed. That coupling — fix one thing and you disturb another — is exactly what makes real landings hard.
SpaceX boosters fly an extraordinary routine. After stage separation the booster flips, fires a boostback burn toward the landing site, coasts through the upper atmosphere, then performs an entry burn to survive re-entry heating and slow down. Grid fins at the top steer it like a guided dart.
The famous part is the final landing burn, nicknamed the hoverslam or suicide burn. A Falcon 9 with one engine lit at minimum throttle still produces more thrust than its empty weight — so it cannot hover. The only solution is to time the burn so the booster reaches zero velocity at exactly zero altitude. Light too early and it stops in mid-air then climbs; too late and it hits the deck. The margin is fractions of a second — which is why it's computed, not flown by hand.
All of it nulls out the same variables you juggle here: velocity, attitude, and position — with no fuel to spare.
Under the hood the game checks all five parameters at the moment the legs touch. It's a simple idea that captures the real challenge:
function isSafeLanding(s) {
return s.onPad // over the green pad
&& s.descentRate < 12.0 // m/s, gentle contact
&& Math.abs(s.lateral) < 7 // m/s sideways
&& Math.abs(s.tilt) < 6 // degrees from vertical
&& Math.abs(s.spin) < 12 // degrees/sec
&& s.fuel > 0; // didn't run dry
}
Miss any one and it's a "rapid unscheduled disassembly." Get all five — and you've done what only a handful of teams on Earth can do for real.
Throttle to slow your fall, rotate to stay upright over the green pad, and touch down slow, vertical and centered before fuel runs out.
Phone/tablet: the three on-screen buttons. PC: arrow keys or WASD (↑ = throttle, ←/→ rotate).
Five must be right at touchdown — descent rate, lateral speed, tilt, spin and pad position — plus fuel as your budget, with wind disturbing you.
It's a simplified 2D model of the same problem SpaceX solves with a hoverslam, gimbaling, grid fins and thrusters.
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