This unique pocket-sized remote-controlled car racing game starts off being more frustrating than thrilling.

Ultimately Touch Racing Nitro becomes a lot of fun to play, but only if you have the co-ordination to master the innovative yet somewhat tricky controls.

DrawRace turned the race genre in the App Store on its head last year with its clever concept and ingenious way of driving a car around a track. TRN from Bravo Game Studios now makes a similar impact on iPhone and iPod Touch racing games.

Touch Racing Nitro dispenses with the services of controls such as a virtual d-pad and buttons for accelerator and brake.

In their place are … well, your thumb.

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Everything is this game is touch-controlled, but not in the conventional sense.

To steer all you do is put your thumb on the screen and your little car will go in that direction.

The speed of your car depends on how far away from it you put your thumb. Put your thumb close and your car will drive slowly, put it further away and your car will go fast.

For the most efficient driving it’s best to have both thumbs at the ready, switching between them as needed.

Launching nitro boosts is the only time you’ll need more than one digit on the screen at the same time.

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It’s a very clever control system, but it does take a lot of getting used to. The learning curve isn’t made any gentler by the tutorial which should teach all the fundamentals of the game but actually provides very little information.

This isn’t a game you’ll be able to jump straight into and immediately drive like a pro. It’s going to take patience and perseverance before you start putting in fast laps.

The hardest parts of driving in TRN are controlling the speed and taking corners. If you’re anything like me you’ll spend a lot of time, at least early on, flying off the track.

Luckily there is a reset button which puts your car back on the track on the multiple occasions it veers off-course, but the game can still be punishing.

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For a casual little racing game TRN contains a decent amount of content.

There are three tournaments to compete in, spread across three distinct environments.

A time trial mode allows you to set lap times on the 18 unlockable circuits in the dozen unlockable RC vehicles.

Leaderboards are provided through the OpenFeint social network system. A nice feature is being able to race against friends’ ghost times or the best times of other people.

There are no muliplayer option which is a shame because it would be a lot of fun.

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This game boasts some excellent 3D graphics which, with all the vibrant colours on display, makes it very appealing to look at.

The physics in the game are also impressive. The cars zip around authentically quickly – a little too much at times. The way the cars bounce off each other is another very nice touch – there is some real scrapping to done out on the track.

There are a couple of very old games – 3D Stock Car Championship for the Spectrum and the arcade hit Championship Sprint – which TRN reminds me of, in a good way.

While the RC cars in Touch Racing Nitro couldn’t be any smaller, the potential for fun is big – once you get the hang of getting your car going in the right direction and keeping it on the track.

Verdict: 7.5 out of 10 – This thumb-powered game provides a unique racing experience on iPhone and iPod Touch.

Watch a video showing Touch Racing Nitro in action: