How to Solve Marupeke Puzzles
Marupeke is a grid puzzle invented in 2009 by Naoki Inaba. The rules are pretty straightforward. Simply fill in the puzzle so that there are never more than 2 X’s or O’s in a row, horizontally, vertically, or diagonally. Basically, play Tic-Tac-Toe to a draw against yourself.
This particular puzzle is never really difficult, as the observant player will almost always see the next move, although the black cells can sometimes make seeing the diagonal possibilities a little trickier.
Starting from this point, we’ll start showing some simultaneous placements so we aren’t being tedious by drawing out each of them one at a time.
First, we block the two diagonal pairs of X’s. Next, we block the horizontal and diagonal pairs of O’s. And in the third picture, we place an O between the two X’s on the diagonal, and on the top and bottom of the vertical pair.
Can you see the next moves?