Diadoku

Diadoku is a free diamond-placement logic puzzle for iPhone and iPad, built around careful reasoning rather than guesswork. Players place one diamond in every row, column, and color, while ensuring that no two diamonds touch, even diagonally. Each board has exactly one solution, and the game guides players through its rules with a tutorial that includes voice instruction.

The app offers 2,000 levels, ranging from 4-by-4 to 10-by-10 boards, as well as a new daily puzzle and a weekly star league. Players can compete in live duels on the same board, challenge friends, earn trophies, and advance through six leagues. Daily play supports streaks, awards bonus hints every seventh day, and offers three-star goals. Players can also choose a gem avatar and frame.

Diadoku includes light and dark appearances, support for seven languages, iCloud progress saving, and offline level play. Its clean, calm presentation makes it suited to short puzzle sessions or steady progress through a larger collection of logic challenges.