Ball Sort

The basics

Tap a tube to lift its top ball, then tap the tube you want to drop it into. A ball may land in an empty tube or on top of a ball of the same colour; a full tube and a different colour are both refused, and the tube you tried shakes. A move carries exactly ONE ball — unlike the liquid form of this puzzle it never moves a whole matching stack, so you can split a stack to free a tube. The star rating compares your move count with the level's par: par itself is three stars, within five moves of par is two, any other win is one. Hint searches from the position you are actually in, not from the start, and points at the first move of a shortest solution without playing it; when the position is already dead it says so and you should undo. Undo steps back one ball, Restart reloads the level, and the arrows move between levels. Each level's best move count is stored in this browser only.

Objective:

Gather every colour into a single tube. Each colour has four balls and each tube holds at most four, so a level is cleared only when every tube is empty or full with four balls of one colour. There are 12 levels in three tiers — easy (3 colours, two spare tubes), medium (4 colours, two spare) and hard (5 colours, one spare) — and every level shows its par: the fewest moves that solves it, found by a breadth-first search before the level shipped.

Controls:

Tap (mouse, touch or pen, all handled as one tap) a tube to lift its top ball, then tap the target tube to drop it; tap the same tube again to put the ball back. Buttons: prev / next level, Undo, Hint, Restart and Rules. Keyboard: 1 to 9 pick a tube, U undo, H hint, R restart, and the arrow keys change level. Every button is at least 34px tall and every tube at least 28px wide. Add ?level= to the URL to start on a level number or a tier, for example ?level=hard.