Why? Quite a poignant question, that. I put it to Bristol City Council after every roundabout in the city was replaced overnight by a set of traffic lights. It also begged to be asked when blue Smarties appeared, consigning years of tradition to the dustbin for no obvious reason. And every time they change the Blue Peter signature tune, 'why?' is the word that forms on the lips of the nation.

And I'm afraid that, despite employing my powers of investigative journalism to their full, the reasoning behind these three pieces of software remains a mystery. Let's look at the Architecture disks first. They each offer three alternative sets of architecture. There's 21st Century USA, 22nd Century Europe and Moon Base on the first disk, and Ancient Asia, Medieval Times and Wild West on the second. They sound like fun. But all they actually do is change the graphics your copy of Sim City uses to display cities. (And only after endless pratting about with installation programs and blank disks!)

Stadiums turn into rodeos or low-gravity sports complexes, airports turn into castles of space ports, and so on. An interesting exercise, but a pointless and slightly sad one. It's a bit like buying a plastic spoiler and some fog lamps for your Ford Escort 1.3 Popular in the hope that they'll make it go faster.

And what of the Terrain Editor? Isn't Sim City already an 'editor'? Surely that's the whole point? Well, yes. So what the Terrain Editor does is let you handle the process that takes palce while Sim City is displaying the "Terraforming" message. That is, designing the layout of the land, sea and trees that your city will be built on. So you could, if you like, reproduce your favourite piece of coastline (those fjords around Norway, perhaps). You could write your name in trees. And, er, that's it. At £7.99 for all three, die-hard Sim City fans might conceivably be tempted, especially for the collection of demo cities supplied on the Editor disk. But a tenner each? Nope, it seems that, unless you've exhausted Halford's selection of Escort add-ons, or you make a bit of a gaffe and assume you're holding a copy of Sim City itself (which could easily be done - the packaging is very deceptive), you'd have to be stark, staring bonkers to buy any of these.

The Terrain Editor might be good for a few minutes playing around, but that's it. These are trying to milk a game for more than it's worth.