FlOw is an odd — yet strangely compelling — concept. Symptomatic of the kind of creativity that's heralding the PlayStation Store as a haven of addictive smaller games — look at Riff: Everyday Shooter, the ever-expanding PixelJunk stable and LocoRoco et al for more of this — it's a trippy and relaxing journey through, ironically, a pretty brutal process: natural selection.

Beginning as nothing more than a lowly amoeba, your task is a simple one: survive. The gameplay mechanics are simple; about as simple as you're ever likely to see. You're a creature, eat other creatures to get bigger, so you can eat more formidable specimens, and grow further. In-game, this is represented by a sea. Beginning on the sun-drenched surface, a few small blobs are dispatched before you chomp upon a red marker and descend to the next level.

Each new area is slightly visible from the plane above it — just blurred so you can't quite see what's waiting for you — and they get murkier as you descend. Each area presents new, larger challengers, and there's a corresponding blue marker that's the opposite of the red, allowing you to ascend and devour some more lowly life-forms to bolster yourself should you need it before tackling the next challenge.

And that's it. There's six playable creatures, all resembling watery denizens of the deep — you begin as a snake, but take on jelly, manta ray and further alterations of these basic formulae throughout. Each has a special power that makes devouring smaller creatures a little easier. Initially, there's a burst of speed, but later you're given access to spinning suction forces and paralyzing bites. There are six levels of deep-sea diving for you to engage in, before returning to the surface and starting on a new creature.

Control is as simple as the gameplay — tilt the Sixaxis pad in the direction you want your creature to move in, and hold a button down to employ the special ability. The handling takes a while to get used to, but once you do it's a joy — superbly intuitive.

Despite this, I'm not sure that flOw is much of a game. An enjoyable diversion, and a good looking one, yes. It's fun to tinker with, and very relaxing. It's very simple, and obviously won't be able to compete with plenty else that's on the PlayStation Store. Despite this, it's notched up hundreds of thousands of downloads. Very simple then, indeed, but simply very good.