A 4x4 sudoku puzzle has 4 rows, 4 columns and 4 2x2 square regions, one in each corner. Can you create a 4x4 sudoku puzzle with only 4 clues given?
The most common sudoku variant is X-sudoku where the two main diagonals are two extra regions. Can you create a 4x4 X-sudoku puzzle with only 3 clues given?
My answer. The three clues are in bold, italics and underline:
2 1 3 4
4 3 1 2
1 2 4 3
3 4 2 1