### How to play

• Each puzzle consists of a 6x6 grid of numbers, where one number is already selected (black circle);
• Using only logic (no guessing needed), choose the numbers so the sum in every row or column is 9 or less:
• Click once on a number to remove it from the grid;
• Click twice to select it (blue circle);
• Click three times to remove the marks.
• Each number (1 to 9) must appear exactly once;
• A red mark will alert you if the sum in a row or column is more than 9;
• The game ends when there are precisely 9 unique numbers selected on the grid and the sum rule is followed.

### Tips

• If this is your first time playing, try to solve the "very easy" puzzle before playing the other ones;
• You can start by eliminating duplicates of the given number(s);
• If a number appears only once, then it must be in the solution (see Naked Singles in our Sudoku Guide);
• For more strategies that can be applied in this game, look at Naked Pairs and Pointing Pair in our Sudoku Guide. These kind of strategies can be applied to any logic game, so it's worth understanding them.

### Understanding the Importance of Logic in Gameplay

Kyudoku is a game where logic is not just recommended, but necessary for solving its 6x6 numerical grid puzzles. Unlike some other number games that might allow for a degree of educated guessing, Kyudoku requires players to adhere to specific rules to find the correct numbers that will make each row and column sum up to 9 or less. There's no room for error; each number from 1 to 9 must appear exactly once on the grid, and a red mark will promptly alert you if you've crossed the sum limit in any row or column.

The design of the game thus encourages a systematic approach to problem-solving. Players must evaluate the grid carefully, considering how each number they select or remove will impact the total sum of its row and column. This logical analysis becomes particularly crucial because one wrong move can disrupt the balance of the entire grid. It's this aspect of Kyudoku that makes it not only a fun game but also an exercise in logical reasoning and decision-making.

### Benefits for Kids and Adults

Kyudoku offers benefits to both kids and adults, acting as an engaging way to hone problem-solving skills. For children, the game serves as an educational tool that can improve their arithmetic abilities, pattern recognition, and logical reasoning. It introduces them to the basic mathematical concept of summing numbers, but in a challenging and entertaining context. Learning to balance row and column sums within the confines of a grid also teaches them the importance of planning and foresight.

For adults, Kyudoku provides a stimulating mental exercise that can help keep cognitive functions sharp. The game's requirement for a systematic approach and logical deductions could offer mental benefits similar to those gained from puzzles like crosswords or Sudoku. It also serves as a casual yet effective form of stress relief, as the act of solving a puzzle can create a sense of accomplishment and offer a break from the daily grind. Overall, Kyudoku is a versatile game that offers developmental advantages for people of all ages.