I never thought the day would come when I heard these words pass my lips, but… forget Halo 2! Master who? Half-Life 2 just blasted onto the scene as relentlessly as Gordon Freeman on a mission, defying all those who said it wasn't possible and proving just what a trooper the Xbox is.

In all seriousness, there is no fair basis for comparison between Half-Life 2 and Halo 2, as they are two completely different games, sharing only the genre in common. It's like picking favourites between Aliens and The Matrix - they're both groundbreaking science fiction films, but their feel and intent are completely different, and comparing them because they're both sci-fi would be inherently unfair. And thus it is with the two kings of the first person shooter on Xbox. Halo 2's goal is for engaging gameplay, a sweeping, grand storyline that spans worlds and plenty of replay value in both the single and multiplayer modes. Half-Life 2 on the other hand has only one intention: to immerse you into a world so real and complete, so convincing and terrible, that you are there. And in that it succeeds better than any other game that has come before it.

I have very fond memories of the original Half-Life, which I completed on PS2. Despite dated graphics (as I played it years after its release) and intrusive loading times, it was an instant classic that I'd still happily go back and replay even now - although its impact would be significantly lessened after playing the sequel.

Half-Life 2 is a unique game in many respects, but probably the most distinctive is in its presentation. From the moment the opening credits come up on screen, you are in the game, in the shoes of Dr. Gordon Freeman, the hapless scientist who survived the infamous Black Mesa incident and defeated alien invaders from another dimension, taking the fight all the way back to their home world. You gather, from the opening speech given to you by the shady man in black from the first game, that you have been frozen in stasis for a long time, and now you're being placed back into the world for unknown reasons. Appearing on a train running into a huge station, it is immediately apparent that something is very wrong. Guards with full-face masks and a very Nazi-esque attitude are everywhere. A white-haired man's image appears on a huge display screen, spouting what is clearly propaganda to all that are foolish enough to listen. And, if you care to look to your right before heading through the first gate, there's an alien sweeping up on the platform. Yep, things are definitely awry.

The first thing that strikes you, as you walk around the train and the credits appear on screen, is how lifelike and stunning the graphics are. Facial detail has been taken to a new level, with amazing realism and incredible animation when each of the hundreds of people you meet on your journey speak. They blink, they look at you, they show emotions like surprise, happiness, horror and despair. They seem so real that you immediately feel empathy towards them, unlike anything you've felt before in a game. Meanwhile, the rest of the scenery is equally as incredible - sure, the textures can be very basic if you go right up close, but that is a necessary evil to create a landscape of such unprecedented scope and scale on Xbox, and it never in any way detracts from the realism, because the overall effect is like nothing you've seen before on a console - Xbox 360 included, at time of writing!

One of the main reasons that this game is so immersing from the word go is because there are no levels and no cut scenes - you see everything through the eyes of Gordon Freeman and you are as completely clueless as he is with regards to what the hell is going on, learning the situation as he does, as glimpses of things like that janitor alien, and throwaway remarks from the people you meet, which hint at what is to come. When I say that there are no cut scenes, that's not entirely true. There are plenty, but they're interactive, so they're more like set pieces. At many pivotal points of this epic story, you can walk around and look at the scenery while the characters talk to you and explain a little bit of what is going on, and what you must do next. Similarly, when massive events occur, like big attack or the introduction of new enemies, you're in the cut scene as it's happening. This only serves to further immerse you into the game and soak up every detail of these set pieces, far more than if they were cut scenes where your ability to move was replaced with cool movie-like camera angles.

So, you head on to the checkpoint and it's looking very foreboding - the few people in the station are barely clinging to their sanity. They accept their relocation with an air of inevitability, as if there is no other choice. One woman is waiting for her husband, who she'll probably never see again. There's a man walking back and forth, mumbling the same ominous gibberish as he goes, while a second man tells you not to drink the water. After entering the checkpoint, you're stopped and taken into a room, getting a glimpse into what is clearly a torture room, before the guard within closes the viewing slot. Led into the next room, it's looking very grim, until the guard removes his mask to greet you! His name is Barney and he's a member of the Resistance, who's very glad to see you. He sends you through a storage room to help you avoid the checkpoints and you soon make your way into the town square, which is locked down and fortified by futuristic looking barriers with impassable energy shields. Making your way up a fire escape ladder, you carry along a route that takes you into an apartment building - which is shortly raided. A run across the rooftops follows and just when you think there's no way out, a very attractive young woman named Alex comes to your rescue.

Following Alex, you arrive at a secret lab, where Dr. Kleiner, one of your old colleagues, greets you. You gain just a little bit of understanding of just how bad things have got since you've been away, and just how long it's been since the Black Mesa incident. I don't want to discuss the story any further, because I want you to discover it all for yourself. Indeed, at this point I strongly recommend that you stop reading my review and just trust me that this is the must have Xbox game of 2005. If you own an Xbox, you need Half-Life 2. For those of you who haven't clicked on the link to your favourite retail site, what I will say is that every step of the way, the story unfolds piece by piece, teasing and tantalising you with snippets of information - everyone assumes you know what's going on, so you only pick up hints from their conversations and remarks, while events that you witness also allow you to start putting things together. It's a totally compelling story, with a bunch of likeable characters and a truly detestable villain. And it twists and turns brilliantly until the dramatic conclusion.

The gameplay in Half-Life 2 is simply incredible. There are no levels here, only landscapes, and the landscape design is the best I have ever encountered. There are no easy routes or straight paths amongst the war torn and decimated areas; wherever you go, there is wreckage and collapsed brickwork. There are so many excellent puzzles to do with the landscape that just finding your route through each area is a challenge in itself, and a very satisfying one at that. While there is only one way through and in that respect the game is very linear, if doesn't feel at all linear - it feels like you did a great job of finding a sneaky path through a trashed building, or across a damaged sewer system, or around a force field. At every turn the landscape challenges you to search and think, and sometimes you won't believe that the only choice you have is the one ahead of you - wait until you have to cross a massive bridge by working your way across the metal girders underneath it, all the while staring down to the sea - and it's a very long drop!

But the design excellence doesn't stop there - the placement of enemies is superb; sometimes they surge forward in groups, or out from several directions at once, or just lie in wait to catch you unawares. This combination of route finding and gunplay is an unbeatable one, and it compels you ever onward to find out what's going to happen next and where you might end up.

Speaking of enemies, they're very intelligent and brilliantly varied. You begin with the armed Combine troops, the mask-wearing Nazis of the tale - and I got great pleasure in gunning down every one of these sadistic bullies that I could. I don't think I'm spoiling any surprises when I tell you that the Headcrabs make a return - vicious creatures that look like plucked chickens, and attach themselves to their victim's head, subsequently mutating their body. The lurching zombies are one of the most horrifying enemies ever - not because of their twisted, clawed arms or the massive fanged mouth that's formed where their chest and stomach used to be, but because of the muffled screams of agony and terror that come from beneath the headcrabs. The human hosts are no longer in control of their bodies, but they're still self-aware and in a perpetual state of unimaginable torment. They beg you to kill them in barely intelligible moans and screeches, a request that you gladly oblige. Those hanging aliens also return - the creatures that stick to the ceiling and drop their long rope-like tongue down, to hook you in, pull you up and devour you. It's a nice touch that you can feed them explosive barrels, then detonate the barrel when it's near enough to burn the foul creatures.

As the game progresses, more and more formidable enemies appear. There are organic dropships that put Combine troops on the ground, and a variant that's armed with a deadly powerful machine gun. The first time you come up against one of these things, it's a real mission and a half to kill it, I can tell you! Huge insect-like creatures have colonised the sandy shores of the coastline and as you make your way across it, they attack you in droves. There are more, like the Striders, but I'll leave you to discover the rest for yourselves.

The gameplay is constantly changing; no two areas feel the same, thanks to the change in enemies and the feel of the landscape. The first part of your journey takes you on foot across literally miles of an industrial area of the city and through sewer systems to make it to the Resistance headquarters. A part of this section sees you traversing miles of swampland, going through docks and ports, and even across radioactive sludge, in a very cool hovercraft that eventually gains a gun capable of taking out those pesky helicopters that are dropping mines everywhere and shooting you to pieces. Another section sees you driving along the deserted coastline, fending off Antlions and only stopping to search abandoned houses for supplies, or to work your way past the latest Combine barricade or checkpoint. These parts of the game literally allow you to cover miles of ground, giving a sense of scale like nothing else I've played.

Then there's Ravenholm - "We don't go to Ravenholm." And for good reason - it's a veritable house, or rather town, of horrors, boarded up and infested with headcrabs and zombies, completely deserted save for a lone nutcase on a mission from God to show his 'congregation' the light. As you progress, you find ways to make use of things that were once enemies. Mines can be switched to your side and, in certain sections of Nova Prospekt, if you don't place your automated turrets strategically, you'll die for sure - and even if you do place them carefully, you still might die! You get a squad of men to accompany you at times, which comes in very useful, especially the medics. You even get a major foe on your side at one big turning point, but it's such an incredibly cool feature that I can't bring myself to spoil it.

The weapons are superb, and rather than taking the Halo 2 chop and change approach, Gordon is fully capable of carrying the following at once: crowbar, pistol, magnum (so wonderfully powerful that it's a joy to use!), crossbow, shotgun, machine gun, assault rifle (a futuristic and very cool version), grenades and rocket launcher - oh, and the gravity gun; let's not forget the coolest weapon in the whole game! Many weapons have a dual function - the shotgun can fire double rounds, the machine gun launches grenades, the assault rifle launches this wicked bouncing energy ball that vaporises multiple foes in an instant and the crossbow has a great zoom on it. Every weapon looks the business, the reload animations are top notch and they're all great to use, with an accurate targeting system and fantastic effects. Gunfire blasts out of your speakers in full surround sound, completing the feel of every weapon.

But it's that gravity gun that will become a firm favourite, as it makes use of the game's incredible real physics system. Grab a radiator off the wall, pick up a wardrobe, breeze block, explosive barrel, or any other piece of scenery, and then blast it at high speed into your enemy, knocking them dead in one shot if it's heavy enough. Watch in amazement as barrels bounce and roll around, or as breeze blocks smash through windows and fly into the air. Stare in awe as you blast cars out of the way with the secondary function, which simply pushes objects out of the way with tremendous force.

The physics are amazingly lifelike and totally convincing, and they're one of the biggest parts of the graphics that really immerses you. Watch as an enemy falls from a ledge, arms and legs flailing until he lands with a crash, or on occasion a little bounce. The combination of these physics with the outstanding detail on the people (including very smooth animation for running and movement), the amazing enemy designs and scenery that often stretches out in front of you as far as the eye can see, is astounding. The sound effects are just as great too - every enemy screech and noise is distinctive, while you can tell what gun is firing at you just from the sound. The ambient effects are fantastic too. Take the time, out on those lonely coastal roads, to park up on a cliff and just stare out over the sea. Look around at the nearby trees and telegraph poles, as you listen to the wind whistling past your ears, the sea washing over the shore below and the cry of the gulls - and you'll be amazed at just how real it all feels. And how, suddenly, you're feeling a bit isolated. Time to move on…

The voice acting throughout the game is excellent - every character, both minor and major, plays their part perfectly and the script is very well written. As for music, well, there isn't actually that much - possibly another reason why the game is so immersing. When it comes, it's generally very subtle, with ominous themes to rack up the tension in a foreboding area that you just know is going to be hiding some Headcrabs and other nasties, with the occasional blast of full on action music, slightly techno in style with a strong beat. Because of the sparing use of music, it has all the more impact when it comes, but you don't miss it when it's absent.

It's worth mentioning that the controls are excellent - very responsive, judging jumping is intuitive and balancing on narrow beams is a piece of cake. The weapons are mapped out in a very clever fashion too - they're assigned to the four directions of the D-Pad, and multiple presses select the next weapon - so, down for crowbar, down twice for gravity gun, up for pistol, up twice for Magnum and so on. It works like a dream, as cycling through all those weapons with one or two of the coloured buttons would have been unworkable. You have your radiation suit too, which can be charged up, as well as your health, both with wall-mounted units or using medikits and energy cells that are scattered liberally all over the place - you're always rewarded for exploring nooks and crannies with goodies like health and ammo.

Any downsides? Not really - occasionally the learning curve can be tough, particularly when dealing with a high security area full of gun turrets and Combine footsoliders, or when killing a new enemy for the first time, but repeated attempts will see you through. A couple of puzzles had me a bit stumped, but I figured them out after applying some thought. I suppose the frequent loading interruptions, which make you realise how much Halo 2 spoils you, are intrusive at first - but they last only twenty to thirty seconds and you soon get used to them. It's a small price to pay for the way this amazing game has been squeezed onto the Xbox, and I understand that the PC load times can be a lot longer, so it could certainly have been a lot worse!

Half-Life 2 is the most immersing and compelling game I've ever played. Although I've had a lot of games to review in the last couple of weeks, I couldn't help keep coming back to Half-Life 2 on a daily basis until I completed it. That very rarely, if ever, happens to me. In fact, the last time it happened was Halo 2! With groundbreaking graphics that push the Xbox like never before, a totally convincing and stunningly rendered environment and unparalleled attention to detail in every respect, from facial detail to real-time physics, Half-Life 2 will grab hold of you and not let go until its dramatic conclusion. There are so many fantastic moments that will stick with you, like the on-rails tour you get of the enemy Citadel that gives you horrifying glimpses of awful truths, and the super-powered gun you'll wreak utter havoc with that you get towards the end of the road. Half-Life 2 is the closest thing to virtual reality I've ever played on a console, and regardless of whether you like shooters or not, it's an absolute must. Now, where did that pesky Lamarr get to? I know she's around here somewhere…. Aaargh! Lamarr, don't scare me like that…

Reviewed by Geoff Holland for AceGamez (All Rights Reserved).