Headache? Feellng faint? Insatiable bloodlust to kill everyone in your path? The doctor will see you now...

We've always hated going to the doctors. Whether it was for a minor childhood ailment that at the time seemed like we were at death's door, or more recently to the 'personal health' unit of the hospital where the nurse asks you lots of embarrassing questions. And no, thanks, we don't want a lollipop to make it all better. Pariah, the latest shooter from Unreal creator Digital Extremes however, puts a decidedly more enjoyable spin on medical matters.

We could harp on about how FPSs are ten a penny on Xbox at the moment, and how a game has to be pretty special to stand out from the crowd. But Pariah is genuinely different from other Xbox shooters, playing and looking more like a PC title than a console one. We couldn't help but think of, dare we whisper it, Half-Life 2 whilst playing it. 'Blasphemers' the PC crowd may cry, yet here we are, enjoying a stunning-looking blaster that features astounding physics, right in the here and now. And this developer has done its body-flinging best to give Valve a run for its money.

Right from the opening cutscene, Pariah's excellent script draws us into a murky futuristic world of mankind-ending viruses and conspiracy theories. Needless to say, the absorbing plot features more twists than a dancing worm high on ecstasy, so we don't want to spoil the surprises. All you need to know is that you - Dr Mason - wake up, dazed and confused from a crash in hostile lands with a killer virus on the loose. And from the get go, it all goes absolutely bloody mental. Because it's an archetypal doomsday scenario, you won't be surprised to find out flower-collecting kids skipping through sun-drenched meadows are absent from this game world. Instead, desolate wastelands are punctuated with intricately designed, impressively epic industrial complexes. Intelligent level design ensures there's always an elevated position on hand to take a breather and put your sniper rifle to use, whilst the developer has provided just the right amount of cover to ensure a fine balance between tactical gameplay and frenetic all-out blasting.

But it's not all Mad Max meets Blade Runner. The speeding train level, and the episode where you battle an attacking command ship before boarding it, are refreshingly different and will really get your bloodlust flowing. The indoor settings boast great-looking textures and nice lighting, though this attention to detail is somewhat lost in the bigger, blander expansive levels.

The plus side of these environments are the vehicles. Although fun, they're something of a wasted opportunity. Vehicular combat is limited, as is the overall use of the vehicles themselves - it seems they're only present to get from A to B that little bit quicker. The Bogie, for example, is similar to Halo's Warthog to drive. However, Pariah's people carrier is nowhere near as user-friendly to drive as MC's ride, and handles nowhere near as well. It's a laugh to hop behind the beefy rocket launcher and let friendly AI tear around in the jeep (as long as you can stomach the sometimes erratic camera). Yet with you behind the wheel, the Bogie frequently gets stuck on even the smallest of rocks. You'll scream in frustration as it flounders around like a giant turtle atop a poacher's spear. Not the best example of an All-Terrain Vehicle.

Countless games tout the virtues of the Havok engine, though few put it into practice as well as Pariah. It's this fantastic, real-life physics engine that is literally the driving force behind the game's appeal. There's a huge amount of interaction with the environment throughout the game, including a wealth of destructible scenery to demolish. Explosive barrels are an age-old cliché in first-person shooters, yet the stunning physics add a further dimension to this. A wave of enemies advancing worryingly fast up that slope? No problem. Simply give those barrels a couple of shots to tip them down the incline, then either let the bouncing bombs crush your hapless foes or give them an extra blast to detonate in precisely the right place. Enemies also have the same idea; it's truly terrifying to try to push up a staircase with toxic barrels raining down on you. The resulting explosions hammer home the genius of Pariah's ragdoll physics, as enemies are catapulted high into the sky before raining down around you. Indeed, blast a foe point blank in front of a railing and they'll slump backwards, contorting themselves over said railings before tumbling into oblivion. Brilliant.

Pariah's engaging enemy AI also compounds this. The Just A Flesh Wound difficulty setting isn't too taxing, though whack their toughness up to Heroic Measures or Flatlined and they're fearless adversaries with the cunning of an Oxbridge-educated fox stealing chickens from the MI6 co-op. Or double-hard bastards who'll take a mag-full of ammo before going down. Either way, it's not good news for you. Enemies frequently hide behind littered pillars and barrels, all of which can be obliterated to reveal the hiding heathens before dispatching them.

Pariah is one of the rare breed of shooters that features some genuinely jaw-dropping moments, and players will frequently stumble across truly epic setpieces. It's not unusual to round a corner to find swarms of enemies rocking up in combat vehicles, lobbing grenades and plasma orbs in your direction, or emerge from a tunnel to find rival factions tearing chunks out of each other. Similar to the Covenant/Brutes/Flood spats of Halo 2, players can either sit back and let the scrapping parties slowly wipe each other out, or get involved and add to the mayhem.

The tiniest bit of slowdown is occasionally evident, taking the sheen off these incredibly polished moments, though we'll play the understanding boyfriend and forgive Karina and co just this once. After all, she's put out a whole lot throughout the rest of the game for us, eh? And so onto the weapons that make all this possible. Pariah's arsenal is a bit more inventive than your average shooter, and at its core is an ingenious upgrade system. Each weapon has its own merits and advantages, and none are ever superfluous; we found ourselves using a beefed-up Bulldog (the first weapon you'll encounter in the opening scene) right up until the final level. Upgrades make a genuine difference to each weapon - you'll both feel and see the marked difference, and the ability to pick and choose which weapon to upgrade adds a healthy dose of variety to the infected blaster.

The weapons menu is super-quick and intuitive to use, and players can instantly switch guns or assign upgrades even in the middle of a firefight. You can tap the Left trigger at any time to whip out your crunching Bonesaw as a melee weapon, though we found ourselves hardly ever using this, such was the ferocity of our ranged weapons and the absolute abundance of ammo replenishment.

But enough of the single-player campaign. Monogamy is not something Pariah practises and the game features much more than a token, tacked-on multiplayer. A lot of sweat and tears have gone into this side of the title, and the rewards are there to be reaped. Although only five game modes are present in all (Deathmatch, Team Deathmatch, Capture the Flag, Siege and Front Line Assault), the inclusion of super-fly Al bots ensures every match is an engaging pitched battle.

The latter game mode in particular is a real riot, as players engage in a continuous tug of war over a map, trying to gain footholds in bases over the other. A great feature is the ability to swap out your Weapon selection (an assorted two per player) at any point in the game. Powerless to stop the marauding opposition from storming your base? No problem, simply swap your sniper rifle for a hefty rocket launcher and the next time you spawn you will, quite literally, be the king of the hill. That is, until the brilliantly astute AI and your with conspiring mates start flanking you and you have to rethink your tactics...

There's not a huge amount of maps on offer, though they do include your generic close-quarters corridors versus open base-based plains. Nope, what really rocked our world was the innovative and impressive map-making feature. Incredible in detail, players are presented with more options. than a mid-'90s dotcom investor. Once again, Pariah's easy and intuitive controls make this an absolute cinch. Creating a map of this complexity and taking it online against Friends is a huge leap forward in the world of Xbox Live and should be absolutely incredible. It even manages to put the excellent map-maker of TimeSplitters: Future Perfect to shame.

So what's not to love about this lonesome blaster? Well the lack of an instant save feature may irk some gamers out there, and often it's a punishing, repetitive slog from the previous checkpoint should you inadvertently bite the bullet midway through a level.

That said, the game is disappointingly short; we were more than a tad dismayed to finally get our greedy mitts on the fabled (and absolutely terrifying) Titan's Fist weapon, only to use it for a final, short level. We can't help wonder, either, at Mason's curious ability to take a rocket squarely in# the face, yet die if he falls off of anything over four-feet high. The big wuss.

But factor in all its innovations, and Pariah is a game that's greater than the sum of its parts. The single-player campaign, though over too quickly, is immensely enjoyable, and the relentless action never becomes monotonous thanks to the brilliant array of weapons. Multiplayer is a riot, and a massively deep mapmaker to get to grips with compensates for the apparent lack of game options and environments. Stir these together, and we've got the perfect remedy for FPS fever that not even a spoonful of sugar could help taste any sweeter.

1. Looks amazing. Realistic lighting and textures complement a super-smooth game engine and some totally immersive setpieces.
2. Absolutely incredible use of the physics engine. Great ragdoll and particle effects are the result of bone-jarringly brilliant explosions.
3. Multiplayer features pleasingly intelligent bots and an incredibly comprehensive mapmaker that's fully compatible with Xbox Live.
4. An innovative weapons system encourages exploration of the not-so-railed levels to discover weapon upgradesm and ensures variety.

1. Although absorbing and tightly paced, the game is disappointingly short. Competent FPS fans will clock the game in under eight hours.

One of the most technically accomplished FPS titles on Xbox. Like 100mph shooters? Pariah is just what the doctor ordered.