Continuing our theme of offering some of the best brain training exercises... Here's a fun take on the Sudoku puzzle.

We have written about the value of these puzzles before. But here is an engaging online version. The browser-based applet allows you to slide tiles around a Sudoku board and drop them into the grid. There are a number of levels and Sudoku grids to choose from. As well as the usual 9 x 9 grid, the game also includes 4 x 4 and 6 x 6 grids, so even those completely new to the puzzle can get involved.

Try it out at www.jigsawdoku.com