The most classic puzzle in computer science. There are only two rules — one disk at a time, never a big one onto a small one — yet moving the whole tower means learning to treat the stack above as a single unit, which is exactly recursion. First-timers get a three-step lesson from Dino the coach (who talks!), from one disk up to three. Under the pegs, a “way home” path has exactly as many stones as the minimum number of moves (n disks = 2n − 1). 🌱 Easy mode paints every move that gets one step closer green and every move that goes one step farther orange — the exact distance is computable at every position, so the colors never lie. Three disks take 7 moves and suit ages 4 and up; six disks take 63 and challenge older kids.
Only two rules: move one disk at a time (and only the top one of a peg), and never put a bigger disk on a smaller one. Get them all onto the peg with the 🏠 to win.
How to move: tap a peg to pick up its top disk, then tap another peg to drop it. Tap the same peg again to put it back. On a desktop the keys 1, 2 and 3 work too.
Dino the coach: the little dino next to the thumbnail pops up a bubble when there is something to say and tucks it away afterwards. Tap Dino to start the tutorial — three steps (1 disk → 2 → 3), with the disk to move glowing and a 👆.
The way home: the finished tower is “home”. Under the pegs, Dino stands on the stone that shows how many moves are left; a good move hops Dino forward, a bad one hops back. There are exactly as many stones as the minimum number of moves — 7 stones for 3 disks.
Color hints (🌱 Easy only): with empty hands, a green house marks the disk whose move takes you one step closer. Once you pick a disk up, the three pegs turn green (one closer), orange (one farther), grey (same distance) or ✕ (not allowed). The exact number of moves to the finish is computable at every position, so the colors never lie.
Difficulty: 🌱 Easy has the color hints; 🌿 Normal keeps only the “moves to finish” counter; 🌳 Hard gives nothing away.
Stuck? Press “🖐 Show me” — a little hand stays on the disk to move, then points at the peg to drop it on; press again to turn it off. After 10 seconds without a move it points once on its own. “↩ Undo” takes a move back.
Voice: the coach speaks with your device’s built-in voice (on iPhone, the system voice). iPhone needs one tap first before it will talk; turn it off with “🗣️ Voice”.
Too distracting? Tap the 🌼 above the pegs to hide every control, leaving only the pegs and the way home; tap 🌱 to bring them back.
For parents: the Tower of Hanoi is a classic of computer science — its optimal solution isrecursion: to move the largest disk to the finish, the whole stack above it must first move to the spare peg as one unit. With n disks the minimum is 2n − 1 moves: 7 for three disks, 15 for four, 63 for six. The legendary 64 golden disks would take 18,446,744,073,709,551,615 moves — about 585 billion years at one move per second. It is the best story about exponential growth there is.
Start with 3 disks on 🌱 Easy and add a disk after each win. The moment a child notices that one more disk doubles the work (plus one) beats memorising the formula.
