Colour Sort

How to play

Tap a tube to pick it up, then tap another to pour into it. Tap the same tube again, or press Escape, to put it down.

You can pour onto a matching colour or into an empty tube, and nothing else. A refused pour costs you nothing.

U takes a pour back and R puts it forward. H shows one pour worth making.

Rules and controls — Zerdly's preset

This game has variants. These are the rules Zerdly plays by:

• Every tube holds the same number of units.
• You may pour into an empty tube, or onto a tube whose top colour matches what you are pouring.
• A pour moves the whole run of matching colour at the top — or as much of it as fits. You never choose the amount. This is the rule that separates this puzzle from the one-unit-at-a-time versions.
• A tube is sorted when it is full of one colour. Uniform but not full does not count.
• Empty tubes are fine, and are the room you have to work in. The puzzle ends when every tube is either empty or full of one colour.
• Pouring a finished tube into an empty one is legal and achieves nothing. There is no rule against it.
• Undo and redo are available in every preset.

Presets

• Starter — Four colours and two spare tubes. Enough room to experiment, and short enough to finish in a minute.
• Standard — Six colours in the same two spare tubes. The room stays the same while the sorting gets harder, which is where the game starts to bite.
• Expert — Eight colours in deeper tubes. A tube holds five, so a run can be longer than anywhere else — and a pour always moves the whole run.
• Daily Sort — One puzzle a day, the same for everybody, built from the date.
• Relaxed — Six colours with a third spare tube. The extra tube is not a hint — it is somewhere to put a mistake.

Tips

• Count the run before you pour. A run of three into a tube with room for two leaves one behind, and that leftover is what turns a tidy board into a stuck one.
• Keep a spare tube genuinely empty for as long as you can. An empty tube accepts anything; a tube with one unit in it accepts one colour.
• Finish a colour completely rather than half-collecting several. Every full tube is a tube that stops getting in the way.
• Look at what is UNDER the top band before you commit. The shapes are there so you can, and the buried bands decide what your next three moves can be.
• If you are stuck, undo rather than restarting — the position two pours ago is usually the one that went wrong, and a hint from there will tell you why.

Privacy and local play

Everything runs in your browser. Your current puzzle, your settings and your best times are kept on this device only, and the button under the board clears them without touching any other Zerdly tool. No account, no sign-in, and nothing about your play leaves the machine you are on.

Questions

How much pours when I tap a tube?

The whole run of matching colour at the top, or as much of it as the destination will take. You do not choose the amount — that is the rule this puzzle is built on. If three reds sit on top and the target has room for two, two go across and one stays behind. Some other versions of this game let you move one unit at a time; this one does not, and planning around that is most of the skill.

Can every puzzle actually be finished?

Yes, and not because of an argument — because each one was solved before it was handed to you. The board is built by mixing a finished set of tubes backwards, and that on its own does NOT guarantee anything: pouring is not reversible in the way it needs to be, and on a cramped board most reverse-mixed positions turn out to be dead. So every candidate goes through the solver, and anything that cannot be finished is thrown away rather than shown to you.

Why is a tube not finished when it looks finished?

A tube counts as sorted only when it is completely full of one colour. Three matching units with a gap above them means the fourth is somewhere else, and the puzzle will not end until it comes home. Empty tubes are fine — they are the room you have to work in.

Why does every band have a shape on it?

Because the colours are not enough on their own, and we measured that rather than assuming it. The eight liquids were checked under three kinds of colour blindness, and at least one pair cannot be reliably told apart by hue. So each liquid carries its own shape, on every band rather than just the top one — reading what is buried under the top is most of the game. You can switch the shapes off if you prefer, and the game will still work; it will just be relying on colour to tell you things.

Does a hint ever send me the wrong way?

No. It is worked out from the position you are looking at right now, not from where the puzzle started, so undoing a few moves and asking again gives you an answer about where you actually are. The search is breadth-first, which means the pour it shows is genuinely on a shortest route home rather than merely a move that works.

What makes Relaxed different from Standard?

One extra spare tube, at the same six colours. That sounds small and it changes the game completely — a spare tube is somewhere to put a mistake, so Relaxed forgives the kind of pour that ends a Standard puzzle. It is also, oddly, the slowest preset for the computer to work with: more empty space means far more positions to consider.

Why does Expert have deeper tubes rather than fewer spare ones?

Because taking a spare tube away does not make the puzzle harder, it makes it impossible. On eight colours with one spare, only about seven boards in a hundred can be finished at all — so a preset built that way would spend its time rejecting puzzles rather than making hard ones. Expert adds colours and a fifth level to each tube instead, which means runs can be longer than anywhere else, and a pour always takes the whole run.

Can I pour a finished tube into an empty one?

Yes. It is legal and it achieves nothing, so nothing stops you — inventing a rule against it would be a house rule this game does not need. If you do it, the puzzle is in exactly the position it was before, just arranged differently.

How does the Daily work?

One puzzle a day, the same for everybody, built from the UTC date rather than your local one — so it changes at the same moment everywhere rather than at your local midnight. It is regenerated from the date rather than stored, which is why the generator version is part of the key.

Is anything sent to a server?

No. The puzzles, the solver, the hints, the sounds and your progress all run in your browser. There is no account, and clearing this game's data leaves every other Zerdly tool untouched.

Related interactives

• Traffic Escape — slide the cars aside and find the way out.
• Path Pairs — join matching letters without crossing, and cover the board.
• Block Fit — place the shapes that come, and keep the board breathing.
• Number Link — connect the pairs and fill every square.