Of all the refinements the first-person shooter has enjoyed, the pithy post-death war quote at the start of the mission was the quickest to outstay its welcome. After all, the Oxford Dictionary of Quotations has only so many entries about war, and the same old lines have been seared into the darkness between our virtual lives for years.

In Call of Duty 4: Modern Warfare, Activision debuts a whole new stock. In keeping with the modern setting, and clearly designed to break free from WWII's stagnating pool of scenarios, none of the new quotes has appeared before. Sadly, these are variously tenuous, like Virgil's careworn "Fortune favours the brave", and plain irrelevant, such as James Joyce's "Mistakes are the portals of discovery".

Change isn't always a good thing.

The good news for Call of Duty fans, however, is that not much else has changed. Aside from some narrative details and a single high-tech mission, you could squint at Modern Warfare and almost mistake its contemporary backdrops for Norway or Northern France in the early 1940s.

In story terms, the focus has shifted from Hitler to Islamic terrorism. In practice, this entails a mix of close-quarters combat in streets, ships and metallic complexes, and a few set-piece sessions at the trigger of a mounted machine gun, against artificial intelligence enemies and multiplayer friends alike.

The action is entirely first-person, and you control the perspective of your soldier by moving the stylus on the touchscreen. You motion forwards, backwards and from side to side with the D-pad, and fire with the L shoulder. A grenade icon sits at the left of the touchscreen, as well as a gun and a space which is sometimes filled with a pair of binoculars for bringing artillery down on tanks, and at other times a hand for using objects.

It's not an immediately intuitive control scheme, and its problems are compounded by the fact that the command for looking along the barrel of your gun – two swift taps with the stylus – is all too easily issued by mistake in the heat of battle.

In fact, the first couple of hours in Modern Warfare's expansive but bland world are not especially impressive. Enemy soldiers stand planted to the spot or move in manacled routines, and there's a glaring discrepancy in the amount of damage they can do depending on their weapon. A full machine gun clip, point blank, has about as much force as a small swarm of bees, but a single round from a sniper rifle will kill you.

Your own gun, meanwhile, is scarcely more lethal unless you manage to make a headshot, but a melee thump with the stock of a rifle means instant death so that, unusually, the back of a gun is deadlier than the front.

However, if you've looked at the score already, you'll know that Modern Warfare gradually wins you over, because you eventually get better at playing it. It's true that headshots are the only way of ensuring a quick kill, but as become more proficient with the stylus something strange happens: you actually start to get them.

Zooming-in ceases to be unwieldy with time, and after a few hours movement is so flowing and intuitive that you find yourself manoeuvring for the best angle of approach as you enter an environment, firing in controlled bursts to group your shots, and crouching to increase accuracy. In other words, it stops feeling like a DS first-person shooter.

The missions are punctuated by mini-puzzles and turkey-shoot sections, either from fixed emplacements or from the back of vehicles. The best of these, from the side of a helicopter, lasts the better part of a level and gives you the chance to let fly at clusters of exploding barrels, vehicles, and scores of hapless swarming enemies while screams and gunfire tumble from speaker to speaker. The game gathers pace as it goes on, growing more cinematic and grandiose as it careens towards its conclusion.

There's only one real break in the first-person action, and that's a nod to Modern Warfare's modernity. Using high-spec military technology, you have to carry out a series of consecutive tasks from a distant vantage point at night using fancy instruments and night-vision. Here, enemies and friendly soldiers are white grubs, and you have the power to flatten whole buildings or pick off individual men. This brief military omnipotence is vaguely creepy, and it's a shame there's only one level in which to explore it.

But, after all, Modern Warfare is less modern than the title suggests. In truth, there's very little to distinguish it from the first linear Medal of Honor game way back in 1999. Given the limitations of the platform, however, that's much more of a compliment than it sounds.