This time all the numbers are there right from the start - you just have to paint out the right ones so that no number appears more than once in any column or row. But watch out - you can't paint two adjacent cells, and all the remaining white squares must be connected.

Sounds simple?

See if you can spot sandwiched pairs and triples, isolated and flanked pairs, corner- and mid-quads, corner/edge/mid-closures and the tricky HWings! If you're good, test yourself against the time-challenge mode, or practice on millions of boards over three difficulty levels and nine board sizes.

• New! Advanced rule 'Impossible Pairs'
• New! Enter your own boards, and see how they can be solved!
• New! Load and save boards
• 27 million possible boards, generated and play-tested using genetic algorithms and a Mersenne Twister! (but all solved with logic and no guesswork of course!)
• Easy, medium and *hard* difficulty levels
• Nine board sizes from 5 to 13 square
• Unique scrollable board & bird's-eye view
• Hint system, solve next step and solve board
• Five layers for trial, keep or reject, plus full undo/redo history
• Changeable background themes
• Practice or Time Challenge modes with high score tables