Noby Noby Boy is an acid-trip of a game. You play Boy, an ever-growing bipedal snake thing that's got a serious case of the munchies. Rainbow colours scream out of the screen at every turn. There's a lion/sun that peers into the earth from outer space and doughnut-shaped clouds. I don't know what creator Keita Takahashi does in his spare time, but I'd like to try it.

We shouldn't be surprised. Takahashi is the man responsible for the not quite as bonkers but still pretty barmy Katamari Damacy. Here though, he's taken the madness to a new level. Like PSN game Flower before it, Noby Noby Boy makes you question whether it's a game at all. At first you're not sure what you're supposed to do except just... do. With the two Sixaxis thumb sticks you control the two ends of Boy, pulling him apart to what feels like infinity. Pressing L2 makes him eat the various objects that are found on top of the randomly generated maps, maps that are cubes that seemingly float in space (they don't, but more on that later). And that's it. You eat and eat and eat, and grow and grow and grow and stretch and stretch and stretch. It sounds like a dream I once had while at university.

The graphics are basic, but retain a strange charm, complimented by wistful acoustic guitar music. Everything is cute in that classic Japanese fashion us Westerners are used to seeing from children's television and imported cuddly toys. But, in that classic Japanese fashion, there's an odd menace growling somewhere in the background. There's something disturbing and frightening about the idea of a giant snake-like thing devouring an entire planet.

If the concept and graphics make your brain melt ever so slightly, then Noby Noby Boy's controls will make your hand-eye coordination suffer a heart attack. Because the two ends of Boy are controlled with the thumb sticks, turning the camera left and right is governed by taps of L1 and R1, and zooming in and out handled by holding L1 and tilting the Sixaxis forwards and backwards. It's incredibly fiddly, and doesn't get any easier the more you play. The camera often puts you in impossible to manage situations, and can get stuck underneath and inside objects and the map itself. As Boy gets bigger he gets even harder to control - getting him to jump through hoops can be an exercise in frustration, and it's often difficult to work out where Boy's head is in amongst himself.

Messing about with the game's physics is what it's all about.

Boy winds his way through environments populated by people, cars and other bits and bobs, the design of which are dependent on the theme of the map. You might find yourself in a desert-themed environment, or on picket-fence style map, or an urban inspired map. There are cacti, hoops, gates, spinning wheels - everything is designed to be interacted with in some way, whether it's going through it, snaking round it or just eating it. The game doesn't give you any instructions, objectives or rules. It just lets you get on with it.

So, if you're like me, you might start by stretching Boy so that his two ends reach the edges of the map (you can fall off, causing the game to spit Boy back out from his house), then devour anything and everything, just to see. Devour goats, terrified people, boxes, sharks - everything. Then, when you're bored of that, you might see what you can do with objects too big to eat - like Boy's house or tractors. You might find people riding Boy's back, which is funny, really, when you consider the chances are he'll eat them. You might find people gathering in a crowd to gawp at Boy. You might eventually discover that pressing R2 makes Boy shoot out objects he's eaten from his arse, and that tapping L2 or R2 makes him do a jump glide thing. And once you've discovered that, you might see what happens if you just keep jumping. I managed to get Boy through every cloud doughnut in the sky, creating some kind of sugar-fuelled nightmare. Then I thought, well, why not just keep jumping and heading higher and higher into the sky. So I did.

Eventually, I burst through the planet's atmosphere and was asked to report Boy's "length" to Girl, which is hilarious in a very juvenile way. The heart covered Girl is a giant version of Boy, so huge that she is stretching her way out of the planet towards the moon. The idea is that every player contributes their Boy's length to Girl, who gets bigger and bigger every day. On Girl's back stand thousands of avatars, each one representing a player. You can move along her back, looking at everyone's contribution, and marvelling at how they dwarf your own. Eventually Girl will reach the moon, and from there who knows what Takahashi might do. There's only one planet available in the game right now, but the fact that it asks you to pick the planet you want to travel to is telling. You can even record your exploits and upload them to YouTube. Say what you will about Noby Noby Boy as a game, it's a very cool, and modern idea, and a perfect fit for the innovation-friendly PSN.

This is Girl, growing with every 'length' reported by Boy.

While it's nice to just play, which is really the point, there is a feeling that Noby Noby Boy is nothing more than a physics tech demo. A very good physics tech demo, but, at the end of the day, that's it. Noby Noby Boy might be soothing, cute and compelling in a "what can I do here?" way, but the crucial question is: is it fun? The answer is, somehow, yes. Somehow, bashing at the foundations of the game's physics engine is an enjoyable experience. Noby Noby Boy might not be a game in the way we're used to, but it's entertaining all the same.

Obviously it won't be for everyone. There will be some who won't see the point, who will think messing about with a physics engine is a waste of time, who will reckon that, even at just over three quid, it's a waste of money. While there is a degree of truth to those statements, if you're willing to give Noby Noby Boy a chance, if you fancy something a little different, hell, very different, you'll find fun from Noby Noby Boy's bizarre world.