Even so, shooting guns is only a small part of the game's rich palette. Certainly, parts of the game find you in familiar territory - gunning down Combine soldiers with headshots, fending off zombies with a crowbar - it's like you never left. But this kind of traditional FPSing occurs only in moments, carefully weighted segments defined by the game's flawless sense of pacing and surprise.
Just as you finish marvelling at one bullet-riddled set-piece, another huge gearshift sees you dodging rocket fire in an amphibious airboat, beating Manhacks (flying buzz saws) away with a crowbar, hurtling along a coastal highway in a turbo-powered dune buggy, building a bridge out of physics objects or leading a squad of rebels in a pitched street-battle. The action shifts and surges marvellously, never giving you time to tire of one gameplay style and always keeping you guessing. If Rome is Total War, Half-Life 2 is total action.
Indeed, the game is so varied, it's difficult to name all the great gaming moments. Think of your favourite moment in any top shooter, and Half-Life 2 will almost certainly have something to equal or better it. Max Payne 2's explosive shootouts and cunningly placed fuel barrels? Matched. Call Of Duty's epic, intense street battles? Beaten. Doom 3's terrifying zombie corridors? Out-spooked, and with the Gravity Gun in hand, a hell of a lot more fun too. Indeed, Half-Life 2 could claim to beat every other shooter out there at its own game, not to mention doing stuff you've never seen before. It is, quite simply, the ultimate shooter experience.
Of course, the action would be but a mindless killing spree without a strong story to hold it all together, and here Half-Life 2 shows perhaps its greatest genius. As promised, I'm not going to give away too much - the script, the plot, the unfolding scenario are all there to be discovered, not read in PC ZONE. But what I will say is it's not what you're expecting (unless you read the leaked script on the Net, in which case you get what you deserve).
The world of Half-Life 2 is very different from the one we left behind. Many years have passed, and the events since have seemingly cast Black Mesa into insignificance. Where Gordon has been is only hinted at - somewhere away from the affairs of the world it seems - but upon his return, the battlefield has shifted.
It's no longer a simple case of Xen versus human. Under the aegis of a mysterious alien-human tyranny known as the Combine, the world has been transformed into a terrifying police state. Think 1984 meets cold war Russia meets Star Wars-era Galactic Empire, replete with Stormtrooper-like Combine soldiers.
I'll stop there, mainly because I'm being deliberately light on details, but also because the game itself is even more obscure. Most of the back-story and political situation are shown rather than told, with the details left to you to decipher. You're never spoon-fed or patronised - there's no clumsy PDA device with reams of emails to trawl through or a mysterious helper character giving you clues over a voice-com. The narrative simply emerges naturally through the course of the gameplay.
The whole thing is extremely elegant, and manages to keep you intrigued long after you've finished playing. In fact, I'd go so far as to say that after 30-something years, the medium of gaming has finally found its true narrative voice - a mode of storytelling that doesn't mimic cinema or graphic novels or anime, but rather blends elements of all of them to create something unique to videogames. The original Half-Life may be famed for weaving narrative seamlessly into the gameplay, but that was a clumsy hack job compared to Half-Life 2. Deus Ex, Half-Life, Max Payne 2, Halo - all these were but stepping-stones: this, for me, is when interactive storytelling comes of age.