A playground for the robot’s jump physics — the same movement he uses everywhere else on the site, with every setting put on a slider. Nothing you change here affects the robot on the rest of the site.

Controls

Arrows or WASD to move, Up or Space to jump. On a phone, use the pads at the bottom. Tap versus hold changes the arc. On the default tuning a tap gets you about 180px up, holding about 327px. You can also drag the robot around and fling him.

Coin Rush

Collect ten coins as fast as you can. The clock starts on your first move, so you get as long as you like to read the route first. Reset becomes a retry button during a run.

Most coins sit on a platform, so you take them by landing. Some float above one, too high for a tapped jump — those are the ones you have to hold for.

Picking the robot up and carrying him doesn’t count, and nor does one where you changed the tuning partway.

The ghost

Once you’ve set a time in a room, your best run replays beside you as a faded robot, so you can see where you’re losing it rather than just reading the clock afterwards. Only a faster run replaces it. Turn it off in Settings if you’d rather run alone.

Times and the board

A run in the daily room joins today’s board, which the result screen shows you — no names: nothing is asked for or stored that could say who set a time.

Both only count on the Site default tuning — a time set under Moon gravity isn’t comparable with one set under the real physics. Any other tuning still plays perfectly, it just shows as unranked.

Par and scoring

Every room has a par time, worked out from its own route. Beat it for gold, or come in under half again for silver and double for bronze.

The board ranks scores, not clocks, because the daily room is sized to your screen and a phone and a laptop play courses of quite different lengths. Your score is par divided by your time, times 100 — so 100 means you matched par and higher is better. Only your best each day counts.

The daily room

A fresh layout every day, generated from the date, so everyone gets the same room on the same day. It’s built upwards from the ground, each platform within reach of one below, so it’s always completable on the default tuning. Outside a run, coins still appear one at a time with nothing to lose — it just gives you a reason to jump about.

Wall slide, and off the top

Hold into a wall in mid-air and he slides down it at a steady speed instead of dropping. You can also fling him clean off the top of the screen, same as on the rest of the site — a marker at the top edge shows how far up he is, and he always comes back down.

The platforms (tuning lab room)

Every numbered platform sits at a fixed, measured height, so “can I get up there?” is the read-out. They’re deliberately not in ascending order, and each has clear ground beneath it.

• 100 / 150 — anything clears these, a tap included
• 205 — a held jump clears it, a tap doesn’t
• 305 — needs Site default; Anvil and Underwater can’t
• 410 — past Site default and Ice rink; needs Rocket, Moon or Flea
• 480 — Moon or Flea; Rocket falls just short
• 550 — Flea alone, and only on a tall enough screen

The unlabelled ledges are purely to play on. Rungs that wouldn’t fit your screen are dropped rather than squashed, tallest first, so a short or narrow window shows fewer.

The sliders

Settings has a preset menu — Site default is the real robot, and the silly ones (Moon, Anvil, Rocket, Ice rink, Underwater, Flea) are the quickest way to feel what the numbers do. Underneath are the eleven constants themselves:

Jump

• Gravity y — how hard everything is pulled down. Lower is floatier: higher jumps and a slow, drifty fall.
• Jump velocity — the upward shove at take-off, and the biggest single lever on how high you get.
• Ascent force — held — extra lift while you keep the jump button down. Push it further negative and holding carries you a very long way up; bring it up to meet Fall force and holding stops mattering at all, which is where the tap-versus-hold feel disappears entirely.
• Fall force — extra downward pull. Higher cuts a tapped jump shorter and gives a snappier landing, without changing how high a held jump reaches.

Air

• Air accel — how quickly you pick up sideways speed in mid-air. Low feels sluggish to steer, high feels twitchy.
• Air steer cap — the top sideways speed steering can reach in the air. At or below walk speed you land roughly where you expected; well above it and you sail past platforms.
• Air friction — drag applied every frame. Higher bleeds off speed faster and flattens the top of the jump.
• Wall slide speed — how fast you slide down a wall while holding into it. Well under falling speed reads as a controlled slide; near it and the wall stops mattering.

Ground

• Walk speed — running speed on the ground.
• Walk ramp — how many frames it takes to reach that speed from standing. Six feels direct; forty is two thirds of a second of legs going nowhere.
• Grip — how well his feet hold the floor, and so how far he coasts when you let go. 1 is the real robot; below that he slides, and 0 is a skid measured in screens. It has most to say at high walk speeds.

A tuning you’ve changed is kept in the page address, so you can bookmark one you liked or send someone the link.

Measure overlay

Measure overlay, in Settings, adds gridlines, platform labels, a jump-arc trail and the numbers behind all this — worth ticking while you’re moving sliders about, since it’s how you see what a change did.

On screen you get a jump line (height reached, time in the air, distance travelled) and a walk line (how long you took to reach walk speed, and how far you coasted after letting go). Settings then shows the fuller reference: predicted figures from a model of the tuning against measured ones from your last jump and walk. If the two disagree, measured wins.

Rungs also light up as you tune — a rung the current settings should clear gets a bright cap, so you can walk the ladder up with a slider without jumping once.