How to play
You pilot a small lander that is falling toward a rough, moonlike surface. Touch down on one of the flat landing pads without breaking the craft. You have a single tank of fuel for the whole run, so every second of engine time counts. After each landing or crash a new landscape is generated and the lander is launched again with the fuel that is left. The run ends when the tank is empty and the lander is down.
The camera starts wide so you can see the pads, then zooms in smoothly as the ground gets close. The world wraps around: fly off one side and you come back on the other.
Rules
A landing counts only if both feet are on the same pad and all three readouts are inside the limits at the moment of touchdown. A readout is green with an OK mark when it is safe, amber with one exclamation mark when it is a little too high and red with two when it is far too high.
| Measure | Safe landing | Soft landing |
|---|---|---|
| Vertical speed | 2.5 m/s or less | 1.25 m/s or less |
| Sideways speed | 1.5 m/s or less | 0.75 m/s or less |
| Tilt | 8° or less | 4° or less |
Anything else is a crash: too fast, too tilted, a foot over the edge of a pad, or touching rough ground. The lander breaks into line debris and the crash costs 100 units of fuel.
Scoring. A safe landing earns 100 points and a soft landing 150, multiplied by the pad: ×1 for the widest pads up to ×5 for the narrowest. A soft landing adds 50, and a fuel bonus of up to 100 rewards a landing that burned little fuel (one point is lost for every three units used). Later landings have rougher ground and fewer wide pads. Your five best scores are stored in your browser with the date, and a score set with the trajectory hint on is marked hint.
Settings. Gravity can be Lunar (1.62 m/s²), Medium (3.71) or High (9.81), with the engine scaled to match. Terrain difficulty changes the roughness and how wide the pads are. The optional trajectory hint draws a dotted line showing where the lander will go in the next few seconds with the engine off.
Controls
- Keyboard: ←/→ (or A/D) rotate, ↑, W or Space thrust, P or Esc pause, H hint, M sound, Enter start or continue.
- Touch: two round buttons on the left rotate the lander and the large button on the right fires the engine. They work together, so you can turn and burn at once.
- Mouse: use the buttons under the playfield for pause, sound, hint and to abort the run.
How the physics works
Gravity pulls the lander down with a constant acceleration g, and there is no air to slow you. With the engine off, the speed after t seconds and the distance fallen are:
v = g · t
h = ½ · g · t²
On the Moon a drop of 100 m takes about 11 seconds and ends near 18 m/s, far above the 2.5 m/s limit. The engine pushes along the lander’s own axis, so tilting the craft turns part of the thrust sideways. That is the only way to move horizontally, and the lander never loses sideways speed by itself. If you drift at 5 m/s you must tilt the other way and burn to cancel it. Do it early: it costs less fuel and does not disturb your descent. Hovering needs the engine at about g divided by the engine power, roughly 39% of full thrust in lunar gravity.
The suicide burn
The most fuel-efficient descent is to fall freely as long as possible and then fire the engine at full power at the last moment, timed so that your speed reaches the safe value exactly at the ground. It is called a suicide burn because there is no margin: start too late and you cannot stop, start too early and you waste fuel hovering. It is cheap because gravity does most of the work for free.
Tips and strategy
- Cancel your sideways speed early, high above the ground.
- Pick a pad before the final burn. A wide ×1 pad is a safe choice early in a run; narrow pads pay more but leave little room.
- Use short taps on the rotate keys to fine-tune the tilt, and keep the lander nearly upright for the last 20 metres.
Frequently asked questions
Why does the lander keep drifting sideways?
There is no friction in space. Speed only changes when something pushes on the lander, so you must tilt and fire the engine to slow down.
Why was a slow landing a crash?
Check the tilt and the pad. Both feet must be on the same pad and the tilt must be 8° or less.
Is my progress saved?
The top five scores and your settings stay in your browser only. Nothing is sent anywhere.
Does it work on a phone?
Yes. Three large buttons appear under the playfield and the page does not scroll while you play.