Like Sudoku, O'Ekaki provides an entertaining test of one's logic, using a grid of boxes as its playing field. But rather than leaving the player with nothing more than a bunch of numbers, O'Ekaki ends with a flourish: an interesting piece of art that evolves as boxes are darkened until the puzzle is successfully completed. It's a puzzle that utilizes both sides of a person's brain! And each puzzle's title is an amusing clue to the picture that will finally emerge.<br><br>Simple instructions are included at the front of the book to get one started along with some useful tips. The puzzles challenge on several levels, from one pencil--beginner--to five pencils--expert--all resulting in a sometimes quite elaborate picture. Many of the O'Ekaki puzzles in <i>O'Ekaki Heaven </i>have a spiritual theme to their outcomes. Still, don't be fooled; some of the more difficult puzzles can be downright devilish!