This new Xbox Live Arcade game - the debut release from Dundee-based Proper Games - is all about sheep herding. Thankfully it's a puzzle game though, not an exquisitely detailed realistic simulation (let's hope that no game developer ever runs with that idea) so there is a fair amount of light-hearted gameplay involved. I have therefore been spared the terrors of realistic shepherding but have I been saved from a lacklustre game? Fortunately I have, as FLOCK! is truly life-changing, just for the whole uniqueness of the experience, if not for its almost-perfect quality.

The first unusual element of FLOCK! is that there is absolutely no story laid down in stone for you to follow. There is just one simple statement: there are aliens and they want farm animals. They're mainly interested in sheep, but cows, chickens and pigs are also ripe for the plucking. Unlike other games that start with an introduction and then funnel you down a particular path, FLOCK! simply states "There is the concept, make your own story out of it," allowing imagination to run rampant. So whilst your initial reaction might be disappointment at the lack of a story, there are infinite possibilities for your own interpretation of what might be behind the aliens' interest. Peaceful gamers could suggest that the aliens are saving the helpless critters from catastrophic floods and other natural disasters. On the other hand, the aliens, lacking the brute force for open conflict yet still hankering for galactic domination, could be trying to drive humans to extinction by taking away their food source. Maybe the idiotic aliens think livestock are the dominant species on this planet and just want a friendly chat in their ships. These are all valid reasons. However, I formed a much more convincing (in my mind at least) theory. I believe the aliens are abducting cows, sheep, pigs and chickens so they can sneak onto our planet in disguise, studying it and our military effectiveness, biding their time until a large enough force has landed before dealing a swift decisive blow, crippling our defences and leaving our homeworld open for a full scale invasion. In fact, I am absolutely sure that all cows are actually angry and violent aliens in disguise - aliens with ray guns!

Whatever the reason, the mysterious aliens require someone to pilfer the cuddly critters. Who could be charged with a task of such monumental importance? You, of course - always trust a gamer for tasks of this magnitude - and thankfully harvesting livestock is, on the surface, quite simple. Most animals have an innate and ungodly fear of flying saucers that cast beams of light on the ground and you are provided with just such a craft to collect them. Position your UFO behind the sheep and, God willing, they move forwards, away from the shining light beam of evil. I say "God willing" because the cowardly creatures have a tendency to scatter; they usually go where you instruct, preferring to flock together into a big group for safety in numbers, but there is always one who will stand up to your authority or crash into some scenery and get left behind, at which point things become more difficult.

To rescue the lost lamb you need to turn your ship, which is a simple control-stick-tilt away, but as the UFO moves round, the beam shifts position, terrifying the herd and opening gaps for even more critters to run amok - perhaps even forming a completely separate flock for you to corral. It's apparent that even advanced technology does not make the occasional animal abduction any easier for our fun-loving aliens. That's not the end of the hardship either, as trying to get your saucer back behind the animals is taxing, pushing the flock back and undoing all of your progress if you are not careful; you need to fly the ship around the sheep and then swoop back in from the rear, like a military general leading a flanking manoeuvre on an overwhelming enemy army.

This might on the surface seem tactical, slow-paced and difficult, but this is just not the case and you'll get the hang of how to move the UFO successfully and herd sheep into flocks without frustration after a few short trial and error sessions. The game never loses its challenge though, as the pesky animals always find ways to defy you, but it does become a lot easier with practice. Aiding you in this task is an amazing level structure, starting with an un-baa-leviably easy (the developers' joke, not mine) one and progressing up into terribly taxing, tricky nightmares, building up your sheep-herding skills in stages before unleashing the real challenge. This effortlessly smooth difficulty curve is complemented by a very strong 'one more go' factor; I'm so hooked on FLOCK! that you're lucky I stopped for long enough to write this review! This is brought about by the regular introduction of something new and unfamiliar, be it a super-fiendish scarecrow that horrifies nearby sheep (sheep really are afraid of a lot of things) or magical catapults that can be used to hurl animals over indestructible stone walls. Increasing this "what's coming next" excitement, all successfully completed levels unlock a different object to be used to create your very own levels or occasionally reward you with an upgrade to your flying saucer, such as a tractor beam to move loose obstacles out of the way.

Completing a level and getting those rewards isn't as easy as getting animals from one end of an area to another though, as per the usual sheep-rustling activity (not that I have stolen sheep before, of course), because the pesky farmers have a very twisted idea of farm management and have laid out their farms - hedges, fences, pigsties and all - into absurdly complex puzzles. This means that each level is one large puzzle for you to solve in a similar way to the one puzzle per level style of World of Goo. For example, each different animal type has its own unique ability, which often impacts the way a puzzle needs to be solved. Sheep, made out of cotton wool, shrink when squirted with water, while cows are heavy enough to move large objects but have short tempers and often stampede, charging forward uncontrollably. Chickens can glide across gaps between land, allowing them to reach places that other livestock cannot, but they have a natural aversion to poo piles, scattering when the pongy stuff appears in their path. Pigs (my favourite animal) specialise in causing problems because they're completely spherical and roll about at quite a pace, making them harder to steer. They also love to roll in poo - as is only proper for pigs -temporarily forgetting the terror of your flying machine as they cover themselves in muck. Examples of puzzles that arise from these characteristics include getting sheep wet so that they can pass under low obstacles or knocking down fences with ferocious bovines.

Another similarity to the fantastic World of Goo is that the end of a puzzle is marked not by a Goo pipe but by a towering, orange, bell-like mothership dropped off by the UFO you eventually pilot at the start of a level. This engine of doom highlights the ground in front of its door with a light green glow and any animals herded into this area are sucked inside. Every pet vacuumed up in this way knocks one required animal off the quota for level completion, and when this falls to zero you no longer need to abduct any more animals; pressing the Y button reattaches the UFO to the mothership, initiating blast off and displaying a level score.

Of course, your score is of vital importance for an Xbox Live Arcade game, primarily because it gives you bragging rights in the pub but also because aliens favour those with high scores. A crucial factor as you fight to stay on their good side is time; aliens hate inefficiency, so the quicker you fill your quota of livestock, the better. The best pilots, rounding up animals in painfully quick times, are rewarded with a gold medal, while the less adept have to settle for a silver or bronze, though sometimes you are awarded nothing. You can progress to the next level even if you don't receive a medal, albeit with a diabolically low score, so you should definitely consider trying that level again, until you have some sort of medal under your belt.

Time is not the only factor that affects your score, though; after you've fulfilled the quota and completed the level, you can always delay launch while you round up the leftover animals for a small yet worthwhile increase. This doesn't impact the time for successful abduction either, so if you have achieved a medal then there's no need to worry about losing it. In addition, you also get some extra points from a host of other activities, including destroying objects such as trees with your UFO's tractor beam (when you unlock it) or rolling the spherical pigs into pinball bumpers - Pork Pinball! It's not really worth spending hours doing this though, unless you love getting every single point that a level offers, as the increase is small in comparison to the time factor in filling your quota.

You wouldn't expect to see pinball bumpers on a farm but they (quite bizarrely) blend beautifully with the surroundings. It is this eye candy that I find exceptionally difficult to describe. The crux is that everything in the world is stitched or stuffed like a soft toy. The ground is a patchwork quilt of greens, yellows, oranges and browns, depending on the seasonal setting, and sometimes you arrive in the night, blanketing everything in darkness and making the farm all the more spooky as the glow of fireflies lights up pockets of the land and sea. All levels take place on islands, surrounding by water that sloshes about realistically and looks gorgeously clear and warm as it flows over brightly coloured pieces of coral. However, be careful not to herd any cuddly critters over the edge and into an early grave.

The island farms are populated with all manner of items too, such as fences, trees, boulders and bridges, all rendered in cartoon style, in keeping with the stuffed and stitched theme. The best visual feast though is the insanely cute and cuddly animals, such as the fluffy white sheep, little more than bouncing cotton-wool balls with eyes. Also worth looking out for are the very British Highland cows, looking like a cross between Dougal from The Magic Roundabout and a mop, with thick stands of hair draped over their bodies. All this fluff and string does give the appearance of something intended for young children, which may discourage some players, though the stylised visuals do make it stand out from the crowd. It's really down to personal preference whether the soft toy style works for you, but I feel it's superb.

The animals all sound like their barnyard equivalents too; cows go moo, sheep bleet, chickens cluck and flap their wings about madly when scared (this review seems to have degenerated into a children's book). The music shares the same quality and when you first play the game it's impossible not to jam along with the hillbilly style country soundtrack. The main menu music and some mid-level tracks remind me of the outrageously funny alien comedy film Men In Black - a great setting for the humourous nature of FLOCK! The minor niggle I have is that, at its default level, the music is simply too loud, requiring a quick trip to the sound options menu. In addition, the flashy music can, on some levels, be slightly too overpowering, drowning out the wonderful ambient effects and getting in the way of your thought process as you attempt to plan a route that solves the puzzle.

There are over fifty levels included, so you won't have to worry about this very original and well-executed arcade game being over in a flash. However, most levels should be over in under ten minutes, so you'll speed through them fairly quickly if you're determined - one weekend would be ample time for an avid gamer. However, doing this is slightly missing the point of FLOCK! - it's a game to dip into for a quick dose of fun and not something designed to keep you playing for days on end, with replay value coming from perfecting your captures for those elusive gold medals and high scores. There's also a co-operative multiplayer to bolster the lifespan, where you and your friend each have your own UFO and must work together to herd a flock of animals into the mothership. This often involves extra tasks that one UFO would struggle with, such as gates that must be held open by a tractor beam or large rocks that are too unwieldy for one UFO to move. Unfortunately, this multiplayer is for local play only, meaning that you need to have a friend or family member handy. The lack of online play is disappointing and for some may even rule out the mode altogether, but the multiplayer does not really add anything extra, it just expands on a very solid foundation.

Aside from co-operating with nearby friends, there is the scores feature I mentioned earlier; you can replay levels for the highest score or to maintain your place at the top of the leaderboard. Perhaps the most exciting thing though is the inclusion of a map editor, allowing you to create your own levels. You don't have to be a technical guru either, as levels can be constructed with ease; you simply select an object and drop it in a suitable position. Most of these objects (trees, hedges and what not) are only useable after certain single player levels have been completed however, so you'll have to get a fair way through the game before you have access to the cooler bits and bobs. These extras come in extremely handy when making the farmyard equivalent of Rome, yet they are definitely not essential - you are free to start your mad creations as soon as you switch on the game! Thankfully you can test drive your level at any point, to make sure you are actually building something that works. With your cartography finished, you can upload your masterpiece to Xbox Live for others to explore, giving the game almost limitless replay value if the feature proves popular.

I can't keep talking till the cows come home though (I demand a promotion after that quality pun) [Are you kidding? Consider yourself lucky to still have a job! Ed.] so it's time to sum up this odd yet enjoyable gen. I have very rarely enjoyed an arcade game as much as I enjoyed FLOCK! - it's cute, enjoyable, original, funny, quirky and a little bizarre. What more could you want? The only real drawback is its longevity; how long it will last really depends on whether or not you're interesting in perfecting your performance, whether you have someone to share the co-op mode and how much the gaming community will use the map editor and upload their creations. This is an enjoyable game to dip into, a fun puzzler that offers some great pick up and play fun. There is no evolving storyline that unravels after completing levels, no complex plot twists and no evil villains to thwart; FLOCK! instead epitomises what games were invented for in the first place: pure and simple fun.

Reviewed by Tom Clark for AceGamez (All Rights Reserved).