Sweep the floor until it turns into space.

It only does one thing

You drag a broom. That's every control in the game. The head sits under your finger and turns to face the way you're moving, and any dust in front of it rides along.

The first time you play, there's a little pile in a ring with a ghost finger showing the stroke: SWEEP IT INTO THE PILE. Do that and the pile gets eyes. DUST BUNNY! Then the game says FEED IT. MAKE IT BIGGER. and leaves you alone.

Anything a body touches, it eats. So the bunny eats dust and turns into a PEBBLE, then a MOON, a PLANET with oceans, a GAS GIANT with a ring. Each one names itself when it happens. You can sweep small bodies into big ones too.

One thing you'll figure out in the first minute: dust near the very ends of the broom head gets kicked off sideways, so keep the pile in the middle of the head. Zig-zag hard and the head turns sideways and drops the lot.

Then it lights

Get a gas giant up to 700 motes of dust and it lights. The game stops for a moment, the screen goes white, rings blow out of the new sun, and the game shouts A STAR!?

When the white clears, the floorboards are gone. The room is night sky, the dust is starlight, and there's a sun with a face in the middle of it. You're still holding a kitchen broom.

How soon? I wrote a bot that grabs dust at random and sweeps it, loosely aimed, at the biggest thing on the floor, and ran it 40 times. It lit its first star every time, between 8.9 and 20.2 seconds in, usually around 12.5. Slow it down and make it sloppier and the typical star moves to 18, then 23 seconds. A bot that scrubs at random never lit one in 40 tries. The star comes from sweeping toward something.

Space changes the rules a little.

• Nothing stops. On the floor, dust you push slows down fast. In space it keeps drifting.
• Loose dust and small bodies slowly circle your sun. They don't fall in on their own, though. You still sweep them in.
• Suns are hot. Sweep close to one and the bristle tips burn. Hold it there and the broom head is down to 40 percent of its width in under two seconds, and it stays that way for the rest of the run. You can't push a sun, either. The broom goes straight through it.

Past the star

The ladder along the bottom of the screen has two more rungs after STAR. The game shows them as ??? until you've reached them, and I'd rather you saw them there first. If you want to know anyway:

Show me what's past the star (spoilers)

A star that keeps eating turns into a BLACK HOLE at 1,250 motes. Light a second star and the two drift together on their own. That makes one too.

Then it comes after you. About a second after it forms, the hole starts drifting toward your broom, and it picks up a little speed as it eats. Get the middle of the broom, the spot under your finger, onto the black disc while it's down and the run ends: SWALLOWED, your broom went into the black hole. You keep your score. The bots never got swallowed, but only because I wrote them a dodge: they lift the moment a stroke would bring the head near the disc. With the dodge off, the loose bot got swallowed in 35 of 40 runs and the thickest-dust bot in 20.

Here's the one thing worth knowing. It can only take the broom while your finger is down. I parked a lifted broom dead centre on a hole for five seconds and nothing happened. Put it down there and the run was over on the very next frame.

Feed it 95 percent of the room, which is 1,710 of the 1,800 motes, and you get the last rung. The whole universe falls back into one dust bunny on the floorboards, and the broom sweeps it under the rug. The card tells you how long it took. That's worth 5,000 points plus 100 for every second left on the clock.

Ninety seconds

A run is one 90-second shift. The clock waits for your first stroke, so the title screen is the live room and you can look around first.

Your score is everything you've built, weighted by how far up the ladder it got. A planet's dust counts three times, a star's six. When time runs out you get DING! TIME'S UP and a line about how close you were, something like "your STAR was 38 motes from a ???". The ??? stays until you've seen what it is.

It remembers your best score and your best finish time in this browser. Tap to sweep again and you're back on a dusty floor in under a second.

What I measured, and what nobody has done yet

Every star and finish time on this page comes from bots I wrote, running the same code that's in the box at the top. They're not people. Each one played 40 runs.

The star is the easy part. Every bot that sweeps toward something lights one. The finish is different. Past the star there's one thing that can end a run early, and I wrote the bots a reflex that dodges it. With the reflex, the loose bot finishes 37 of its 40 runs, and the thickest-dust bot finishes all 40, about 16 seconds sooner on a typical run. With the reflex switched off, those numbers drop to 2 and 20.

So I won't tell you the end is easy. The fastest finish I've seen from any of them is 28.2 seconds. That's the number to beat.

Here's what hasn't happened yet. Nobody has played this with their own hands, on a phone or anywhere else. I built it, a test harness drove it with real mouse and touch input, and I looked at the screenshots. Nobody has listened to the sound either. It's all made in your browser while you play: a swish that rises with speed, little notes as dust gets eaten, a short climbing run for every new rung, a big chord when the first star lights. There's no music. There aren't any players. You'd be one of the first.

Questions

Do I need to install anything?

No. It runs in the browser, with no account and no ads. It keeps your best score, best finish and which rungs you've seen in this browser only. Nothing gets sent anywhere.

Does it work on a phone?

It's built for one thumb held upright, and the automated touch run went from the first screen to the end card. No person has tried it on a phone yet. There's no mute button on screen, so on a phone the volume buttons are your mute.

How long is a game?

Ninety seconds at most. Less if you finish early.

Can I use a mouse?

Yes, it plays the same: hold the button and drag. In full screen, R starts over and M mutes.

What is the dust actually doing?

There are 1,800 motes. On the floor, loose dust doesn't pull on loose dust at all. A body tugs a little on dust right beside it, more like static cling, and 10 motes packed into one small square make a dust bunny. After the first star there's no floor friction to speak of, the pull gets stronger, and everything loose gets nudged into circling the biggest sun. Mass is counted exactly: every mote is either loose or inside one body, every frame. It's a toy model, not astronomy.