Sudoku is the classic logic puzzle, made small and friendly for children. The first boards are 4×4 and use smiling fruit instead of numbers, so even a four-year-old can play: every row, every column and every box needs one of each fruit. Tap an empty square, then tap the fruit that fits (or drag the fruit onto the square). A piece that fits hops in with sparkles. If it doesn't fit, it gives a gentle wiggle and goes back, and the same fruit that is already in that row, column or box hops up to show why. There is no red cross and no timer. A little wombat helper sits beside the board. It cheers when a piece fits, points when it has an idea, and holds a hint bulb: tap the bulb and the right piece jumps into place. Each stage is a few puzzles in one place. Finish them and the stage is clear: stars, confetti and a new board colour to collect, then you travel straight on to the next place: a garden, the beach, snowy hills, candy land and space. The puzzles grow gently. First come fruit boards with only a few gaps, then 4×4 boards with the numbers 1 to 4, then 6×6 boards with six fruits, and then 6×6 boards with the numbers 1 to 6 for older children. Every stage you clear wins the next board colour, from Mint and Berry to Rainbow. It teaches real logic: not guessing, but working out what must go where. It works with touch, a mouse or the keyboard, and scores are kept on your own device.