Sekuta

Sekuta takes the form of 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.

Sekuta is a simpler form of Sakuro, although that doesn’t make it easier to solve – it can be more challenging because there are fewer clues.