With parallels to a cliff-hanging season finale in a top-rating TV show, Half Life 2 made us desperate to find out what really happened to Gordon and Alyx atop the mighty but Combine citadel. Did they vaporise into their component parts, as we expected? Or did they suddenly sprout wings, fly off and have 10 kids? What will happen? Who will win this frenzied contest over humanity? Stay tuned for the next climax inducing instalment: Half Life 2: Episode 1!" Okay, so I did mean to sound like the voice-over bloke from Iron Chef, so bite me.

Barney mi boy, where ya been?!?!

As we all know and come to expect from Valve by now, they certainly take their lovely time releasing titles. But rather than have us patient gamers wait another six years, they have kindly taken just eighteen months to release the latest title which follows on the footsteps of what was the best release of 2004, Half Life 2.

I'm still not sure on the correct term to use for this game; is it an expansion to Half Life 2, or simply a new game, which happens to be based on the original, but in a bite-sized format? The mind spins, but regardless, this latest release is but one of a trilogy of episodes that promises us more furious thrusting and shaking of our trusty crowbars to last us till the end of 2007. Mind you, with Alyx back in the picture, I'll shake whatever bar she wants, just to keep seeing her lovely smile.

Due to a sudden change of events and with the help of Dog, Alyx's trusty mechanical pet, you'll soon find yourself back inside the citadel you so desperately tried to escape previously. I can't help but mention how I love that darn citadel. It must be one of the finest looking and imposing structure ever to grace our screens. Its cold metallic edifice shines with an inhumanity that's visually spectacular and monstrously effective. It's huge, it's beautifully creepy and it's also about to explode in your face due to a core meltdown, hence your required presence back inside the nightmare.

War of the World's never had it this good...

This time around, the citadel's interior has changed dramatically since our last visit. Impressive explosives, destruction on a gigantic scale, debris continuously raining down upon the hapless duo, as well as malfunctioning systems and huge gaping holes within the ravaged hulk, all impress upon you that speed is of the essence. And what better way to slow down progress than with good measure of combat flavoured with a generous dollop of problem solving.

In the beginning stages of the game, you will be smacked across the head with a healthy 2 by 4 dose of déjà vu. The game forces you, understandably, to follow the same linear route along the same pathways to the same locations within the ravaged hulk as seen in Half Life 2. But to make the walk to the core more interesting than playing a round of golf, you'll be faced with impressively scripted sequences as well as a whole range of imaginative puzzles. These puzzles are straight out of the Gospel according to Half Life. Kind of hard at first glance, but given some thought and a nice cold beer, the brain eventually rolls over for a tummy tickle, giving us the stubbornly obvious answer.

This is a good time as ever to highlight the main difference within Half Life 2: Episode 1. Unlike the previous two Half Life titles where players managed most of the game alone, this time you'll have Alyx along for company. Aside from the odd part where she's forced to stay behind while you choof off to open a door via a series of air ducts or some other fiendishly devised method, you'll be stuck to each other like two peas in a pod. I was quite impressed with how she now shares centre stage alongside Gordon. In terms of helping you progress through the game, she's an angel with a steady gun hand. You'll often find her leading the charge, always hitting on target, while I usually ended up shooting at those scary light fixtures scattered about the place. Evil places those ceilings. Never know what may be lurking behind those pesky light bulbs. Even though you'll find her scaling obstacles obviously way too large or suddenly becoming a trained marksman as well as being able to cope with an unrealistic quantity of pain from all manner of enemies, this new Alyx certainly adds a new dimension to the single-player FPS experience.

As well as performing well on the battlefield, Alyx's personality seems to have undergone a slight shift. She comes up with some unexpected one-liners, which were good enough to make me laugh at often bizarre moments. It's fairly obvious that Valve have placed a touch more emphasis on the romance between Gordon and Alyx, as well as gifting her with a new broad range of lines and animations. By virtue of adding in a nice swag of believable human reactions to the conditions affecting Alyx, you'll end up giving more thought to Gordon and Alyx's predicament with respect to keeping them alive or turning them into a tasty side-dish for the antlions. But here's assuming you're not some kind of heartless rock that happens to play games. Maybe I'm getting soft with age, but I appreciated the extra depth.

She wants me bad, I know.

Once the melting core issue is successfully tackled, the next path leads underground. Of course, underground is usually a good place to stick in some nasty creatures and this is where the action hots up, as well as the heart getting a good workout. The meat supplying the Gordon and Alyx grinder is essentially the same as in Half Life 2, but with a new addition. Combine soldiers have now combined with zombies, resulting in a Zombine. Packing a grenade, these brutes end up being your main focus in any combat situation. Let them come close and the resulting explosion usually means death.

Staying underground, and tying in with Alyx's new tough girl image, you'll find the torch becomes very useful. Shine the beam onto incoming enemies and Alyx goes into overdrive, picking off targets with ease. Of course, being battery powered (thank god for rechargables), torches tend to die out faster than you'd hope. What happens when the light goes out ... well, I'll leave to your imagination. It's wicked fun.

At this point in time, you'll probably have one question that you want answered. What's new? Well, funnily enough, I'm happy to say not much. Why mess with what worked perfectly in Half Life 2? Sure, the graphics have been tweaked (which I'm getting too shortly) and Alyx seems to be on the human equivalent of nitro-glycerine, but it's pretty much the same boat, down a different river. Even the arsenal remains the same; rocket launcher, crossbow, grav-gun, the usual variety of guns and so on.

One red eye is way cooler than two normal eyes

Visually, the game is a sumptuous feast. Nothing I've played so far looks as incredible as this game. Depending on what your PC is capable of, you'll be drooling over the very latest HDR lighting and motion effects, as shown in last year's 'Lost Coast' tech demo. Moving from a darkened room to the sunny outdoors usually takes the eyes a bit of time to adjust, so you'll certainly appreciate the effect in-game when moving from the subterranean hell to the streets of City 17. Alyx's body and facial animations are superb. In moments of despair to shouts of joy, her emotional state is perfectly matched with beautiful facial and body animations that left me smiling in appreciation. Even NPC's seem to have received a once-over from the artist's brush. From the spectacular lighting effects of the core (you really need to check out the core in close-up detail – incredible stuff), the depressed ravages of City 17 to the almost claustrophobia inducing lighting effects of the torch while battling underground, you'd think your watching a top-budget Hollywood extravaganza.

Of course, nothing looks as good if it sounds bad and Valve have done the impossible by improving what was already a great audio experience within Half-Life 2. The pumping music was as fine as you'd find on the racks of a music store. Driving beats were helping you punch through scores of enemies, while the incidental ambience perfectly matched the unfolding visuals on screen. Voice acting was, as ever, impeccably professional with a very diverse range of voices taking the experience to a whole new sonic level. Call me strange, but my favourite piece of audio is beautifully emitted from the Striders. Don't know why, but just like a good horror flick, their haunting howls raise the neck-hairs every single time.

I know I keep regurgitating the old Hollywood line, but seriously folks, if you had plans to head off and watch yet another crabby piece of over-hyped pile of poo at the cinemas, then please save yourselves the bother. Some complaining types might cry foul over the fact that 5 odd hours is too short for a game, but I like to equate it to a film. Apart from watching Gandhi, what can possibly be better than 4 or 5 hours of the best effects, awesome action, solid vocal performances, kick-arse sound and as a bonus, all in the comfort of your own home?

Seriously, if this is the way forward for future game releases, striving for such high-quality output as proven possible by Half Life 2: Episode 1 and released within an acceptably short time frame, then I say bring it on baby, cause this reviewer wants more.