A ball can only go onto the same color or into an empty tube — so to reach the one underneath, you first park the one on top in an empty tube. That is exactly the idea of temporary space and ordering in programming. First-timers get a three-step lesson from Dino the coach (who talks!); a “way home” path under the tubes shows how many moves are left, and 🌱 Easy mode paints “one closer” green and “farther” orange. Counts are shown only when the shortest solution has really been computed. Every puzzle is made by un-sorting a sorted rack, so it is always solvable, and there is an Undo. Three colors suit ages 4 and up; six colors challenge older kids.
Rules: move one ball at a time (only the top one); a ball can only go onto the same color or into an empty tube; a tube holds at most 4.
How to move: tap a tube and its top ball floats up; tap another tube to drop it. Tap the same tube to put it back. Number keys work on a desktop.
An empty tube is “temporary space”: to reach a ball underneath, first park the one on top somewhere else — the same idea as a temporary variable or a stack in programming.
Dino the coach: tap the little dino for a three-step tutorial (1 move → 3 moves using the empty tube → three colors), with the ball to move glowing and a 👆.
The way home: everything sorted is “home”. On the stone path under the tubes, Dino stands on the number of moves left.
Color hints (🌱 Easy only): a green house = one move closer, grey = same distance, orange = farther away, ✕ = not allowed. The numbers come from actually computing the shortest solution; when that cannot be computed nothing is colored, so the colors never lie.
Some moves cannot be taken back in this game: a wrong move can cost several steps or leave nowhere to go. No worries — “↩ Undo” brings you back, and “🔄 Retry this one” restarts the same puzzle.
Difficulty: 🌱 Easy is a few moves from sorted, with color hints; 🌿 Normal is messier and shows only the count; 🌳 Hard is the messiest and shows nothing. Every puzzle is guaranteed solvable (they are made by un-sorting a sorted rack).
Symbols: each color carries its own symbol (●▲■★♥◆) so it is playable without telling colors apart; you can turn them off.
Stuck? Press “🖐 Show me” — the little hand points at the ball to take, then at the tube to drop it in.
Too distracting? Tap the 🌼 above the tubes to hide every control.