Web Dimension is difficult to pigeonhole because, like Psychedelia, to which it has similarities, it doesn't drop into any convenient categories. Activision describes it as an 'evolutionary experience'. There is no beginning, no end and no rules, all of which is rubbish, because there is all of these things.
There are three phases all based around the web of the title. You begin with a grey web of the title. You begin with a grey web and a number of organisms which shift around it, painting colourful paths as they go. You have a musical note which you move around with the joystick. Your objective is to reach the nodes of the web before an organism does, thus freezing it. That's not quite as easy as it sounds, because should you run into the coloured path of the organisms there's a burst of light and you're back to the beginning. Immobilise them all and it's on to the next phase.
In Phase two the web is blue and you have to stabilize the energy clutters by moving over them. This time you're painting the coloured trail, and if you cross it you get that cosmic flash of light.
The final phase includes level after level of sparkling creatures and groovy music, evolving from the web. Wacky. Quite whether it has any lasting appeal I'm not sure, the colours are good and the music is excellent, as it was in Rock 'N Bolt. But its lack of any really appealing gameplay may prove limiting. If a truly addictive little game was lurking among all that sound and colour I'd say it was a great game; but it's just a rather expensive novelty.