Jonny goes on a donkey ride to Hell.

Just a few words of warning before I begin. This game is horrible. Shockingly nasty, upsetting and disturbing. It's a brutal, visceral, experience and deserves that red 18 upon the box.

Experience is certainly the watchword there. See, some games are good, some games are great, and some are experiences that need to be had regardless. Doom 3 is lucky enough to fall into two of those categories. Yes, it is a great game, but it's also something that you need to, well, you know.

There is only one way to play Doom 3. Gibbering like a loon, on your own, in a darkened room, with 5.1 surround. Try not to play it on the easiest level (I went for Marine) or succumb to the powers of the Duct Tape mod (I'll come to that).

Basically, Doom 3 amounts to "You Vs Hell" in the grudge match of the millennia. As an un-named, pretty average marine, you are sent to Mars, where a huge conglomerate is researching into terraforming, genetic research, teleportation and other such inadvisable areas of science. The workforce is spooked, tired, fed up and slowly disappearing, and after some introductory exploration where you get to marvel at the solidity and detail of the environment you find yourself caught in what could best be described as a "situation", when the scientist you're talking to starts trying to eat your face.

At this moment, Doom 3 starts its transformation into one of the most involving, immersive, and nail-bitingly scary experiences you've ever had. With much of the power down, most of the lights in the complex are out, which brings us nicely to one of the title's best gameplay mechanics. You're armed with a torch, and a truckload of weapons, but it's not possible to use both at the same time. This is annoying at first and it is very tempting to download the aforementioned "Duct Tape" modification, as it basically straps a torch to the front of your shotgun and machine gun, but if you avoid this and get used to switching between the torch and your weapons you'll have the more fulfilling and Doom-like experience the developers want you to have.

So most of the time you'll find yourself Muldering through the dark corridors, carefully sweeping the areas ahead with your torch and checking every nook and cranny for power ups or nasty surprises before venturing onwards, switching to a chain gun, rocket launcher, or whatever your weapon of choice is with a quick tap of the F key when something jumps out at you. Which will happen repeatedly.

At first it's just shambling zombies, which aren't that bad and actually just serve as gory entertainment a lot of the time (although they do have a nasty tendancy to lurk quietly in dark corners), but they're soon joined by more advanced (and armed) zombies who were formally your marine buddies (and which get bigger throughout the game), terrifying, ten-eyed, fire-chucking Imps, Pinkies (forget the cute name, these things are the size of a rhino with the temperament of a pitbull), rocket-firing skeletons, horrible spider-things, demonic cherubs and the pant-wettingly large Hell Knights (the thing on the box artwork).

On top of the creature scares the game plays some nasty psychological tricks too. Walls bleed (and sometimes, breathe), satanic pentagrams flash on the floor and every so often something really unexpectedly nasty hits you from nowhere (after one particular scare in the first couple of hours - you'll know the one - I had to hit escape and calm down a bit before venturing onwards).

The sound is, quite frankly, awesome, and is easily the greatest sound design anywhere in gaming right now. It's expertly engineered to make sure that the tension remains taut throughout. You're never far from the humming of machinery, and other noises are constantly to be heard throughout the complex. Haunting laughter, blood-curdling screams, sobbing children, unseen things skittering uncomfortably close to your position. Cleverly, every incidental sound carries with it an air of menace - automatic doors screeching closed behind you sound like the scream of hellspawn (and no doubt the times you think "it's just a door" and don't spin round to investigate are the times when something behind you is about to rip your entrails out) while pipes releasing steam sound uncomfortably like something enormous is breathing down the back of your neck.

The complex is truly alive. Neon lights flicker, computer screens (which can often be interacted with via a very clever interface) reveal important information. Huge, impressive machines whir, pump and blast, and ceiling grilles clatter to the floor in front of your eyes. It may just be an inspired mix of Alien, Half-Life, and Resident Evil, but it certainly works.

There are two ways you can react to this menace permeating the game. You can back off when enemies approach, hide around corners like a child, and play some long-range tactics - which can be risky, drawn out affairs. Or you can set your jaw, tell yourself you ain't scared (yeah right!), pump your shotgun and throw yourself into the fray cackling like a madman.

That is how Doom is supposed to be played. Despite being one of the earliest guns in the game, the shotgun will remain perhaps your best friend throughout. It looks and sounds brilliant - heavy, loud and real, ammo is in plentiful supply, and in the right conditions it's also more powerful than practically any weapon in the game. Almost any enemy in the game can be taken out more easily at close range with the shotgun (we're talking placing the barrel between the creature's eyes and pulling the trigger here) than at longer range with a more powerful weapon such as a rocket launcher.

So it's often better on your reserves of ammo and health (and more fun) to run shouting directly at whatever is in front of you, regardless of how big / terrifying it is, and engage it that way, dodging clawed attacks and forcefeeding it the hot end of your boomstick until it's a pile of dust.

Doom 3, while clearly a masterpiece of design and atmosphere, does suffer the odd setback. It can be quite repetitive, certainly doesn't offer the range of gameplay styles seen in, for example, Far Cry, and sometimes tricks are overused to the point of predictable (for example, when a satanic red fire explodes in front of you, heralding the arrival of an Imp, you can bet yer ass there's one directly behind you too). But this was never about doing something particularly new. This is about showing you the ultimate Doom thrill-ride - a nasty, claustrophobic, tooth and nail fight in gaming's most believable world yet. Plus, unlike many shooters, it actually gets better as it goes on - your descent into Hell itself later in the game does change the playing style somewhat, and certainly doesn't disappoint.

In every conceivable way Doom 3 is a superior product. The game itself, the packaging, but most importantly the fact that its devteam were clearly given enough time to finish this game to the kind of standard we're not used to seeing on the PC, where patches often follow in the days after launch. This is solid stuff, and so far there have been few if any reports of problems on differing systems in the days following launch. Activision and id deserve a pat on the back. And surprisingly the minimum spec isn't as shockingly high as early reports indicated, and it'll run fine so long as you can at least match it.

Yes, Doom 3 is a horrible game, but it's also one that's begging to be played properly - savoured even. Just don't come crying to me with tales of nightmares. You've had your warning.