Platinum Sudoku (Smartphone)

Do you know how many sudoku games there are on the iPhone App Store? Go on, guess. No, higher. Higher. You're still too low!

I'll tell you: 17. That's right, one-seven. And this was last week. Nobody's doubting that there'll be an appetite for the genre amongst iPhone users, but actually sorting through all these games to find the best one will take some doing.

Gameloft's effort, Platinum Sudoku, at least has a track record on its side – the impressive mobile version, which offered a whopping 640,000 grids to solve.

The new iPhone version laughs in the face of its forebear on that score, mind, offering 20 million grids spread across five difficulty levels. It'd take you more than 54,000 years to finish them all at the traditional 'one a day' newspaper rate.

What's more, the separate kakuro puzzle is also included, along with six Challenge variants of sudoku that are unlocked as you progress through the regular grids.

There's also a Custom Grid mode that lets you create your own grids, and a Solver mode that lets you cheat at a newspaper sudoku by getting your iPhone to solve it for you. In short, it has everything that a sudoku nut could want from a game.

Still new to this grid-filling lark? Where have you been? Actually, don't worry, there's a tutorial for beginners, and lessons for more advanced players too, explaining the ins and outs of XY-Patterns, Exclusion and (ahem) Naked Pairs. Again, these are unlocked by playing the main game.

It's truly comprehensive, in other words.

So how does it actually play? Pretty well. The controls will be familiar if you've played the sudoku games on DS's brain training titles. The screen is filled with the grid, and you jab on squares to enter a number, which is done by actually scribbling it onscreen (with your finger in this case).

You can shift between pen (writing big numbers) and pencil (smaller possible numbers) by tapping an icon at the bottom of the screen, and there's also a hint feature if you're stuck.

On the whole, it works well. We had problems with the '5', as the way we wrote it (start at the top and work down) didn't square with how Platinum Sudoku expected us to write it (the opposite).

It can also be a bit fiddly to tap on the right square, especially if you've got fat fingers.

Still, you soon learn to work round these: overall, it's intuitive to play. Plus there's more customisation options than you can shake a stick at: skins, fonts, soundtracks and even grid designs. These too are unlocked as you progress, providing regular rewards.

Control niggles aside, Platinum Sudoku is a class act. The main draw is the ridiculously-high number of puzzles, but around that there's enough polished presentation to put this at the head of the iPhone sudoku crowd. At least for now.