There's a certain sense of grandeur that surrounds The Harvest. It's big, it's bulky, it's frankly rather beautiful at times, but – most crucially – it feels important.

If Windows Phone 7 were a home console, The Harvest would be being pitched by Microsoft as the kind of killer-app worth queuing around the block for on launch night.

Its story of humanity fighting an underground war against the conquering forces of an alien race eager to sap on our flesh is in fact so derivative that it's actually rather comfortable – the opening video that precedes play will be surplus to requirements for most.

Weighty world

The sheer size of it only adds to the feeling that Microsoft considers The Harvest to be something special.

Its desolate Earth, tarnished with the fallout of a nuclear invasion, is exactly the kind of world that could be tapped up for several sequels.

The Harvest is a big game on almost every level you can think of, the opening few minutes laying open a smartly realised desolate landscape that eclipses those delivered in almost every RPG-cum-shooter you're ever likely to encounter on mobile.

The reason The Harvest seemingly comes with such mass is that your primary job is exploration. The phone's accelerometer shifts the view around the level in a slow and steady manner, while holding your finger down anywhere on the screen sends you stomping off in that direction.

Directing your suited warrior as he – or later she – goes on a search-and-destroy mission to what remains of an ancient city is task number one.

As well as picking up teammates to bolster your attack, you encounter scores of Harvesters and their mecha clones, eager to halt your progress and ultimately eradicate what's left of the human race – the Earth Defence Force.

Tap star

The Harvest takes the tap-happy path here. Touching your foes lets you fire on them.

Not every shot will make its target, however. In true RPG-style, The Harvest is a battle of numbers, enemies coming at you in packs – often via ambush – with your job being to prioritise and pulp them repeatedly to knock their health down.

Of course, aside from the upgrades that come as a result (every time your stats rank up, the game lets you assign said points to your Health, Strength, Endurance, Energy, or Agility either manually or automatically), The Harvest also employs a number of special abilities that can help get you out of many a sticky situation.

A burst of speed and an added shield – both activated by a double-tap on your sprite - are skills picked up fairly early on, while perhaps the most useful is a stamp that knocks a whole load of health out of any enemies in the vicinity.

It's this very move, however, that begins to highlight some of the design difficulties that suggest The Harvest is currently a little rough around the edges.

For instance, in the heat of battle it's very easy to double-tap your own character instead of the beasties circling you.

This can actually come to your aid, firing up whatever special ability you happen to have equipped at the time. However, all such moves drain your energy and, as a result, using them all the time can leave you exposed when the next pack attacks.

Button botch

Likewise, given that most of The Harvest's enemies attack from the edge of the screen, attempting to get on top of them before they're in your vicinity can result in the odd accidental tap of the buttons at the bottom of the handset.

That's not a problem if you happen to hit 'back' (which opens the game's pause menu), but it can be a touch annoying when a Bing search pops up mid-game – something that happened twice during our play test.

Add to that some audio difficulties (the game's bold and brassy soundtrack occasionally stutters in the background on our HTC HD7) and you have an adventure that suffers slightly from its sheer ambition.

The Harvest is a game that doesn't want to be labeled as merely for mobile, instead offering up the kind of broad scale action that would have seemed perfectly at home on consoles just a generation or two ago.

If even a fraction of the developers working on the platform show the same level of hunger that The Harvest displays throughout, Windows Phone 7 is set to amass one hell of a roster of games in the months to come.