Sakuro

Sakuro is the double espresso form of Sudoku, an intense shot of intelligent puzzling in a compact form.

The puzzle takes the form a 3×3 grid, with a number in an octagon at the centre of each of the four 2×2 blocks. The solver’s challenge is to place each of the numbers 1 to 9 in the grid, so that the four numbers in each 2×2 block add up to the number in the octagon at its centre. Additionally, the nine squares of the grid are divided into shaded ‘regions’, and the numbers in each region must add up to the given regional totals.