About Sudoku Six
Sudoku Six keeps everything that makes sudoku satisfying and trims the grid from eighty-one squares to thirty-six. A puzzle takes about five minutes, which is the difference between "I might do one" and actually doing one.
How it works
The grid is split into six boxes, each two rows tall and three columns wide. Fourteen squares are filled in at the start, shown in grey. Fill the rest so that no digit repeats in any row, column or box.
Every puzzle is generated fresh and checked to have exactly one solution, so you never need to guess. If you place a digit that clashes with another in its row, column or box, it turns red straight away. You can also type digits on a keyboard.
Solving tips
Scan for the nearly full. A row, column or box with five digits has only one possibility left. One with four leaves two candidates, and a glance along the crossing lines usually removes one.
Work by digit as well as by square. Ask "where can the 4 go in this box?" Rows and columns that already hold a 4 rule out squares quickly, and often a single one is left.
Do not write in a digit you are unsure of. A red digit tells you there is a direct clash, but a wrong digit that clashes with nothing yet stays blue and will mislead you later.
When you are stuck, move to a different area. Each digit you place elsewhere changes what is possible everywhere.
Among HTML5 games, sudoku is one of the few that is as good on a phone as on paper, because tapping a square and a digit is quicker than rubbing out pencil.