Let's put video games to one side for a minute and talk psychology, in specific: flow states. What are flow states? I hear you cry, desperate to know what the hell this could possibly have to do with Osmos on the iPhone. Well, dear reader, a flow state is a mental state of operation where a person is fully immersed in whatever it is they are doing. To dress the idea in everyday lingo, it's being 'in the zone'. It's when your conscious mind takes a back seat to some automatic part of your brain - a mental autopilot, if you will.

Unsurprisingly, games are incredibly effective at inducing these flow states, but a select few have been designed specifically with the phenomena in mind. The most notable of these games is Jenova Chen's fl0w, which I'm sure many of you will remember as a PSN game. It can also be played online for free here, and is well worth checking out if you've yet to do so.

This lengthy introduction finally brings me to Osmos, a game designed with very similar principles in mind. It, too, is an ambient game; you can put on some headphones, find a nice comfy chair and zone out for a little while. Previously released on the PC and iPad, Hemisphere Games' award winning title can now be experienced on the iPhone for the first time. Complete with full iOS4 support, the game looks especially pretty on the iPhone 4's impressive Retina display screen.

Osmos puts you in control of a spherical organism known as a 'Mote'. As this watery mote floats around the dark vacuum of some unknown void, it will bump into other motes. Red motes should be avoided at all costs; they're bigger than you, and will absorb your mote until it's reduced to nothingness. Blue orbs, however, are smaller and can themselves be absorbed, increasing the size of your mote. As you grow, the once dangerous red motes become small enough to absorb too. Just like fl0w, the game has an evolutionary theme at its core.

Movement is a simple case of tapping the mote. Depending on where you tap it, a smaller mote will fly off the edge, propelling the sphere in the opposite direction. Tap multiple times in a row, and a larger mote will be expelled, giving a more impressive burst of speed, but at the same time reducing the size of your mote and thus making you more vulnerable to predators. Some of the latter levels are absolutely packed with motes, and navigation becomes incredibly difficult. The game requires a steady hand and a train of thought more commonly associated with traditional puzzle games.

A down-tempo electronica soundtrack blends with a minimalistic aesthetic to create an almost otherworldly ambience. The game is genuinely absorbing, but unfortunately it's not the kind of title that works all too well on a handheld. Sitting in your bed or favourite comfy chair is fine, but take the game out into the real world - onto trains, buses and loud public spaces - and the experience becomes significantly less enjoyable. Osmos requires very precise movements (which are hard to implement aboard a Croydon tram, I can tell you) and demands that no distractions pull you out of its trance inducing state.

That said, Osmos is still a fantastic little title, one of a rare breed of games that can be described as meditative. A very reasonable £1.79 will get you 72 levels split across two game modes - odyssey and arcade - which is more than several hours worth of 'zoned out' gameplay. It's certainly unique enough to warrant attention, and if you've been neglecting your iPhone as a gaming platform of late, I'd strongly suggest checking it out.