Circulate

It was very difficult not to make the strapline for this review something about playing with your balls getting harder the longer you do it. But I managed to resist, and that's all that matters.

However, should you feel like taking your balls out for a spin (and consider the National Lottery to be nothing more than a voluntary tax), there's no better way to do it that a good hard game of Circulate. And while that might sound like a cheap knacker joke, it's actually quite a descriptive, er, description of Circulate's addictive, casual gameplay.

A 'prologue' to LemonQuest's rotary puzzler appeared on the App Store recently, and although we certainly don't condone charging gamers for demos (even if it is only a few pence), a few minutes on the mobile version and you can really see how ideally suited this terrific game is to Apple's motion sensing handset. The good news is the spin doctors at LemonQuest have done a sterling job at making this analogue game work beautifully with a mobile's digital controls.

Simplicity is king in the valley of the mobile, and for the most part Circulate operates using only left and right keys to rotate the tumbler in which a variety of different kinds of balls are spinning. Much like the handheld ball-bearing mazes of yore, the basic challenge is to control how gravity takes hold of the spheres and guide them to their destinations.

Of course, not every ball has the same destination, and the impressive variety of game mechanics that have been blended into this incredibly simple concept makes for a feverishly addictive experience. Occasionally it can be as simple as grouping balls of similar colour together, or sorting a certain number of each into their own baskets. But even these basic levels are augmented by some clever layouts within the tumbler, such as adding strategic obstacles to your gravity-fed path or arranging the baskets in such a way as to precipitate the escape of previously homed balls.

To keep the variety of the 50 levels as interesting as possible, there's also the addition of ancillary devices, such as black holes, metal balls, 'stop' balls (which you can activate and deactivate, allowing them to roll around or remain stationary), bubbles (which are balls that work in reverse) and bombs. The wild combinations the developers have strung together can make an immensely difficult-looking level quite easy once you've got your head around the puzzle, and simple levels intricately complex when it comes to testing your dexterity.

The speed at which you'll fire through the early rounds makes 50 levels seem like quite a short game, but by the time you've hit the 20th round the hidden sophistication of these cunning thumb teasers elevates the game to a distinct cerebral challenge, every bit as much as a dexterous one. And, since your points are based on the speed at which you complete the rounds (you'll find in some of the later levels you don't score a damn thing), there's plenty of reason to go back over the earlier rounds and have another go at perfecting your technique.

Despite the iPhone's motion sensing controls, it'll still have to work very hard to compete with this awesome mobile version of Circulate.