Everybody plays Sudoku, but I can never remember how to spell it. I suppose it's inevitable that variations on this popular game will come into being, and one of the more interesting ones, visually at least, is Crystal Sudoku.
Rather than keeping track of numbers, with Crystal Sudoku, you are tasked with filling grids with images that don't repeat—little "crystals", I suppose. See how quickly you can complete the puzzle, and save your time to compete against yourself. There are four difficulty levels, so you can keep things interesting as you get better and better.
Crystal Sudoku is a Mac application. It's distributed as a Universal Binary, so it's equally at home on either PowerPC or Intel Macs. It requires OS X 10.4 or later.