A quick history lesson for those who flunked Star Wars school: during the Galactic Civil War, the Empire launched an all out attack on Echo base, a Rebel outpost on the frozen planet of Hoth. The Empire emerged victorious, and the Rebel Alliance suffered heavy casualties. With its speeders, snow troopers and AT-ATs, it's not surprising that the skirmish has been the source of many video game adaptations. THQ Wireless has recently added another to that list with the aptly titled Star Wars: Battle for Hoth; an iPhone exclusive tower defence game that can be currently purchased for just one pound and seventy-nine pence.

Battle for Hoth blends traditional tower defence mechanics with features more commonly associated with the role playing genre. Each unit comes complete with its very own health bar, and will need to be replaced should it become fully depleted. There's a lot to keep track of as a result. You can't simply set up a tower, upgrade it to the max and let it be. You need to be mindful of the battlefield at all times, healing and replacing wounded units when needed. As with other touch screen tower defence offerings, the controls work fantastically well, allowing easy tower placement and quick navigation of the map.

Resources are handled in a slightly different manner to what you might expect. Instead of earning a set monetary reward per kill, you collect tokens dropped at the end of each enemy wave, furiously stabbing at them as they appear on the touch screen. Again, it's a mechanic used to increase player involvement. There's no sitting around and watching your masterful defence strategy unfold - you're constantly collecting, refining and fixing your defence.

While the game is more immediately involving than other tower defence games, it loses some of the strategy along the way. Route planning and unit placement doesn't seem as important to the outcome of the battle - your troops will die anyway, and formation can be refined when you inevitably have to replace them. Thinking time is dramatically reduced too; the experience is frantic. This isn't necessarily a bad thing, but not a quality I personally like to see from the genre.

The App Store plays host to a wide range of exceptional tower defence games (if you haven't experienced the joys of geoDefense yet, make it your mission to do so), making it hard to stand out in the crowd. Battle for Hoth is certainly an interesting take on the formula, adding speed and fluidity to the experience while retaining the core sense of strategy. Star Wars fans will drop the cash on it regardless, but there's enough here to satisfy the urges of serious tower defence players too.