About Colour Sort

A rack of tubes, each holding four units of coloured liquid in the wrong order. Tap a tube to pick up the colour on top, tap another to pour it in. A pour only works onto the same colour, or into an empty tube, and the whole run of that colour moves at once — as much of it as fits. Sort until every tube holds one colour and nothing else.

The difficulty is that empty space is the only thing you have, and there are just two empty tubes. Pour into one carelessly and you have spent the room you needed to unstack something else. Good play is mostly about order: finding the colour that frees the most useful tube, and noticing when two half-finished tubes can be joined to open a third.

Every level here is built backwards from the finished puzzle, which means a solution always exists — a stuck board is the result of your own pours, not a deal that could never be sorted. Undo as far back as you like, take a hint when you want one, and there is one extra tube per game if you have truly painted yourself into a corner. The daily challenge gives everyone the same tubes, with the difficulty rotating through the week, and ranks the day by fewest moves.

Tips to win

• Empty tubes are the whole puzzle: spend one only when it opens a colour you can finish straight afterwards
• Look for a colour whose units sit on top of two or three tubes at once — collecting it frees several tubes in a row
• Joining two part-filled tubes of the same colour costs one move and can free a whole tube
• If you are stuck, undo a few moves rather than taking the extra tube; the run that trapped you is usually three or four pours back