In a previous life, I reviewed videogames for a living. As jobs go, it was a curate's egg. On the one hand, I could legitimately sit around playing games until three in the morning without feeling guilty - even if I wasn't specifically reviewing whatever I was currently playing, it all provided useful background knowledge. It never felt like work.

But on the other hand, whenever I told people what I did, they pulled pained, sympathetic expressions and automatically began treating me like some kind of adult baby, as though I'd suddenly started wheeling myself around the room on an undersized tricycle, gurgling and suckling on a dummy. Because games are for kids, right? So I was essentially a grown man reviewing Mr Men books, yeah?

And when I wasn't viewed as a child, I was viewed as a nerd. How sad my little interests were. How dorky. It was bad enough enjoying the damn things but, being a games journalist, I took things one stage further by developing some understanding of how they were actually constructed. I might look at a new release and be impressed by the polygon count or the draw distance. Apparently this made me a tedious loser, because society decrees anyone who knows anything whatsoever about computers to be a boring idiot, while those possessing a similar level of nerd-knowledge of football or cinema or food are well-informed and sophisticated and sexually attractive and cool.

I didn't realise it at the time, but being a games journo in the 1990s meant I was on hand to witness the birth of several landmark cultural icons first-hand. For instance, back in 1995 I visited the studios of Core Design in Derby to report on the development of a new game starring a female explorer called Lara Croft. Tomb Raider was still in a rough-and-ready state - Lara was running through a grey landscape of textureless polygons - but it was clear this was going to be massive; she already had character.

A year later, I travelled to Dundee to drop in on a company called DMA Design, previously responsible for the popular strategy/puzzle game Lemmings. They were working on a new title partly inspired by a ZX Spectrum game called Turbo Esprit. Turbo Esprit came out when I was 15; I loved it. You had to drive around a city (in a Lotus Esprit Turbo, naturally) seeking out criminals. What made it unique was the sense that the city you were driving through actually "worked". There were traffic lights and petrol stations, roadworks and one-way streets. It was way ahead of its time.

DMA Design's new game featured an even more sophisticated city, with pedestrians and fire engines and its own police force. You could walk around it on foot, committing crimes, pinching vehicles and trying to evade the law. It was called Grand Theft Auto.

It looked very different to the GTA millions know and love/hate today: it was all viewed from overhead, and featured simple "retro" graphics. But it was great. I gave it a rave review, calling it "the gaming equivalent of a smack in the mouth". "Give us a sequel with polygons and cars that flip over," I squealed. Years later, they did.

GTA IV is its latest incarnation. In its first week of release, it made around $500m. It's been rightly, and widely, proclaimed a masterpiece. And it is - at least technically. As far as the script and storyline goes, it tries so hard to appear "adult", it winds up looking downright adolescent. The bad guys are implausibly amoral, everyone shouts "fuck" every two seconds, and the women are little more than haircuts and orifices. In other words, it's like almost any Hollywood action film you care to mention.

But if you can ignore that, there's a wealth of incredible detail and some surprising moments of satire. For example, Liberty City has its own TV networks, which you can sit down and watch if the mood takes you. One channel, Weazel, is a thinly-veiled parody of Fox that features shows such as Republican Space Rangers (a fascistic cartoon in which dimwitted right-wing hicks roam the galaxy exterminating peaceful life forms) and the brashly titled Vinewood Cunts (a reality show about Paris Hilton types). And yes, they use the C-word right there in the game, in the gravelly voiceover for the virtual trailer you watch on the virtual TV in your virtual apartment in the virtual city teeming with virtual life. I don't know quite why, but this really leapt out at me. I don't think I've ever heard the word in a game before. Never mind the polygon count - that's genuine progress.

The one thing everyone knows about Grand Theft Auto is that you can kill prostitutes in it. That's because it's a "sandbox" game in which you can kill anyone you like. Or you can not kill them. Or you can simply drive around slowly, obeying the traffic lights. If you break the law and the in-game police spot you, they'll hunt you down and nab you. Murdering innocent people is neither a) encouraged, b) free of consequence, or c) any more realistic than a Tex Avery cartoon. Nonetheless, Keith Vaz MP is probably standing on his roof screaming for a ban right now, confidently telling the world's press that Grand Theft Auto IV is a dedicated, ultra-realistic prostitute-murdering simulator aimed exclusively at easily corruptible three-year-olds.

He means well, possibly. But he's ignorant. The irony is that every time I read some dumb anti-gaming proclamation by Vaz and co, I get so angry I have to fire up GTA IV and shoot 29 pedestrians in the face just to vent the frustration they've caused. Thank God these games exist, or I would be taking it out on real people.

· This week Charlie speculated offensively and at great length about the Josef Fritzl family-in-the-basement case, none of which can be repeated here. He read The Suspicions of Mr Whicher by Kate Summerscale: "I highly recommend it."