Killer Sudoku

Every killer sudoku in this app has exactly one solution, and you can always reach it by logic alone. If you're stuck, it's the puzzle talking — not a hidden guess the generator forced on you.

Puzzles are generated on your phone, so they never run out. Finish one, start the next. Four difficulty levels go from relaxed cage sums to expert grids with almost no starting digits.

• Pencil marks and a cage-sum helper for narrowing down candidates

• Big, high-contrast numbers that stay readable on small screens

• No energy bars, no daily caps, no locked packs

Nothing else to download after install: the whole game works offline, on a plane or in a waiting room. No account either — open the app and play.

A good fit if you've worn out regular sudoku and want the same logic with a little arithmetic on top.