KenKen: Sudoku plus arithmetic. Each row and column uses 1–N once, and the “3+”, “1−” or “6×” in a cage’s corner says what the numbers inside must make. It trains reasoning, not speed: “this row already has 1 and 3, so this cell is 2” — fill the surest cell first and use it to work out the rest. 50 levels from gentle to tricky (3×3 addition only → 5×5 with all four operations), each machine-verified to have exactly one solution, so 🌱 Easy can tell kids right (green) or wrong (orange) the moment they fill a cell; 🌿 Normal only ticks full cages and flags repeats. Tap Dino for a three-step lesson (he talks!).
Only two rules: every row and every column must use each of 1–N exactly once (1, 2, 3 on a 3×3); a “3+”, “1−”, “6×” or “2÷” in the corner of a colored cage means the numbers inside must give that result with that operation. A single-cell cage just shows its answer — fill those first!
How to fill: tap a cell (it gets a yellow frame), then tap a number below. Made a mistake? Tap “⌫” to erase (in 🌱 Easy you can also tap the orange ✕ on the cell), or just tap another number over it. The arrows also move the selection. On a desktop: number keys fill, 0 or Delete erases, arrow keys move, Z is undo.
Dino the coach: tap Dino’s avatar by the thumbnail for the tutorial — three steps (which number is missing → how a cage works → a whole puzzle on your own).
The way home: under the grid, Dino stands on the stone that shows how many cells are still wrong; a correct cell hops forward, erasing a correct one hops back.
Color hints (🌱 Easy only): the moment you fill a cell you know: a green house means right, orange means wrong. Every level has exactly one solution (all machine-verified), so the colors never lie.
Difficulty: 🌱 Easy checks every cell; 🌿 Normal only ticks a cage ✓ when it is full and correct, marks a repeated number in a row or column in red, and keeps the “cells left” counter; 🌳 Hard keeps only Dino on the stone path (no numbers).
Stuck? Press “🖐 Show me” — a little hand points at the best cell to fill next, and once you select it, at the number to enter; it also points once after 10 idle seconds. “↩ Undo” takes a move back.
Levels: 50 levels from gentle to tricky: 3×3 with addition only → plus subtraction → 4×4 → with × and ÷ → 5×5. Tap “Level N ▾” to jump to any level — cleared ones get a ⭐. Finish without a single wrong entry for a “Perfect”.
Settings: difficulty, level, sound and voice are tucked away by default so little fingers can’t mess with them; tap the 🌼 above the game to open them, tap again to close.
For parents: this is KenKen, invented by Japanese maths teacher Tetsuya Miyamoto — Sudoku plus arithmetic. It trains reasoning rather than speed: “this row already has 1 and 3, so this cell must be 2”; “the cage adds to 3, so it is 1 and 2 — which goes left? Check the column.” Kids discover on their own that you fill the surest cell first and use it to work out the rest — exactly how mathematical proofs and debugging work. 3×3 suits ages 6 and up; 5×5 is for 9+.
