How do you top the most recognisable, genre-defining iPhone and iPod touch first-person shooter? Bump up the graphics, amp up the action, and introduce vehicles - ladies and gentlemen, welcome to N.O.V.A. 2.

It takes only a second to understand the leap this high-definition sequel makes over the first game. Not only are the visuals astoundingly detailed and crisp, but the gameplay has been tweaked and tuned for better control, greater challenge, and heightened action.

N.O.V.A. 2 looks to fulfil the promise of the original with polished action and robust multiplayer.

Shoot first, story later

Eight years have passed since the dramatic conclusion of N.O.V.A. and space military man Kal Wardin has retired. Unsurprisingly, intergalactic political posturing by the human race and the rise of a new alien nation called the Volterites sparks a conflict that pulls Wardin back into the fight - and quite the fight it proves to be.

While I was only able to play through the first level, the action is noticeably more intense than the first game. With such a bombastic opening level, no doubt later levels will throw up quite a challenge as all kinds of powerful new enemies work hard to take you out.

Landing on a jungle beach, you're instantly bombarded by bullets from fast-moving Red Fury troopers equipped with jet packs. Targeting them is tricky given their constant movement, although the crosshairs snap to a target if you're within a millimetre or two.

The auto-targeting feature is actually less forgiving than the original, which promises to slightly increase the difficulty: however, it doesn't overwhelm.

New friends and foes

More Red Fury troopers await inside a military complex, but these are cake compared to the brutish Volterite Psychers that wear cloaking armour. The air glimmers as they stomp around the battlefield, popping into full view when pumped full of lead. They're hearty creatures that require a combination of raw firepower and skilled shooting to defeat.

The weapons remain similar, with the standard issue assault rifle returning. A modified rocket launcher debuts in a harrowing combat sequence against a two-legged mech, whereas new dual-wielded pistols serve as your fall back firearm, offering unlimited ammunition at the cost of low attack power. Several other weapons will appear through the course of the campaign's dozen or so missions.

Joining your arsenal are two combat abilities: freeze and a new attack ability earned later in the game. Unfortunately, I was only able to toy with the freeze ability, which remains unchanged from the first game.

Multiplayer overhaul

Improvements to the flow and difficulty of combat - not to forget more dynamic, varied enemies - top a long list of enhancements, although tighter controls and more robust multiplayer are considerable in their own right. More control options are planned and the general nature of the touch interface feels tighter, more precise.

Multiplayer is being completely overhauled with an eye for building a more progressive, in-depth system in the vein of the superb Modern Combat 2: Black Pegasus.

Experience earned via kills and match wins, ranks awarded with each new level, and an array of new match types including standbys deathmatch, team deathmatch, and capture-the-flag are planned. A maximum of ten players will be supported.

N.O.V.A. 2 promises to be the complete iPhone and iPod touch shooter experience, filling in the gaps and enhancing the fine work of the original rather than starting from scratch. That's fine by us because a polished, well-designed game is more enjoyable than a half-baked original creation.

N.O.V.A. 2 will be available for iPhone and iPod touch this December.

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