Tap Hint. The first step tells you which technique to use and where to look. Tap Show me to see the squares that prove it. In Relaxed mode hints are unlimited; in Challenge mode you get 3 per puzzle.

Select an empty square and tap Notes (it turns green). Now each number you tap adds or removes a small pencil mark in that square. Tap Notes again to go back to placing answers. When you place an answer, that number is cleared from the notes in the same row, column and section.

Relaxed gives unlimited hints. Challenge gives 3 hints per puzzle and counts toward the no-hint achievements. You choose in New game; dailies are always Challenge.

Three new puzzles every day: Easy, Medium and Hard. Everyone gets the same ones. Solve all three in a day for a Hat Trick. The calendar shows the days you played. There are no streaks, and nothing to lose if you skip a day.

Turn on Endless in New game to play one puzzle after another at the same level. After each solve, a card waits for you to start the next one or stop.

Off by default. Turn it on in Settings and a game ends after 3 clashes. Kudo only marks direct clashes in a row, column or section. It never reveals whether an answer is right.

Kudo has 32 personal achievements, shown in Stats › Achievements. If you're signed in to Game Center, they also appear there. There are no leaderboards: Kudo isn't competitive.

Add Kudo to your Home Screen to see today's dailies and your days played this month. Tap a widget to open that daily.

No. Kudo saves as you play and reopens your game paused, right where you left it.

Everything Kudo keeps is stored on your device only. Deleting the app removes all of it: saved game, stats and achievements.

Kudo is in English and Spanish. It follows your iPhone's language. You can change it for Kudo alone in iOS Settings › Kudo › Language.