Sudoku consists of a grid of 3x3 boxes with a random scattering of numbers, within a larger 3x3 grid of these boxes. The idea is that each grid must contain the numbers 1 through to 9, but these must be unique in the box itself and in the neighbouring lines both horizontally and vertically; it is up to the player to solve these 'geometric' equations based on what can and cannot fit. On paper this sounds very simple; in practice it can be very very hard indeed.

The difficulty of puzzles is determined on how much of the grid is pre-populated and how big they are. With bigger grids and fewer numbers populated to start with, the player will have to think ahead far more moves to solve them. Conversely, the smaller the grids and more the populated the squares, the easier the puzzles are to solve. Sudoku is a pure-logic thinking game, and that's where the fun lies.

Buku Sudoku presents these puzzles from both a frivolous 3D perspective and a far more sensible 2D angle. For those not familiar with the game, there are a series of tutorials. Unfortunately, though, they come across as overly complicated and it may well be better seeking an alternative explanation of the rules. Games can be played with the traditional 9x9 grids, the trivial 6x6 grids, an 8x8 variation, and even the excruciatingly painful 12x12 variety. These can be further refined with easy, medium and hard difficulties along with 'timed' or 'casual' (not timed) modes. There's more than enough variation of difficulty, whether the player is a complete novice or a seasoned hardcore Sudokist.

Marking squares with potential numbers needs to be easy and quick to do, because solving the puzzles relies on being able to see what figures work and which figures don't. Thankfully, it's well implemented here. Using the left stick moves the cursor to the differing grids, using the right stick moves the cursor within the grid itself. The player can then mark potential correct numbers with the left trigger or confirm numbers with the right trigger; these can all be toggled or undone, so it's easy and quick to pencil in what the player thinks is the correct series.

With well over 1200 different puzzles to solve, there's plenty here to keep any fan of Sudoku interested. It is, however, difficult to fathom why anyone would buy additional puzzle packs. Given the very rigid rules of Sudoku, it would have been more than plausible to include a random puzzle mode. Instead, it would appear that the future for this title will include additional content at a price. For sure, this might be dearer than buying a paper-based monthly. There is, however, a further part of the game that might sway the fence-sitter.

Buku Sudoku includes online matches, both ranked and unranked, for up to eight simultaneous players. It's not simply a case of solving the puzzles first though, because there are co-op, team battle and dual modes where getting correct lines or squares messes up opponents' grids, and, as such, is almost like Super Puzzle Fighter in play; all for the cost of that Gold subscription and ISP bill. It is a bit of shame, though, that the population of these matches is Spartan at best.

XBLA Sudoku is well implemented, well presented and is enhanced considerably by being able to compete online against other Xbox Live players. At 800 MSPs, with leaderboards, multi-player, achievements and plenty of play-time here, it is a bit of a bargain - but it's not going to convince those not already a fan of the game. Just make sure you've got an alternative music playlist.