The LEGO games' genius is in its dual appeal. Adults love the parody of their favourite childhood movies, and kids love just playing as Batman, Indiana Jones or R2-D2. But the real magic happens when the two come together; when adults play cooperatively with kids - father and son, uncle and nephew, brothers, that sort of thing. Really, the LEGO games are the Toy Storys, Finding Nemos and Ups of the video game world, and developer Traveller's Tales is our very own Pixar.

So you can see why J.K. Rowling's phenomenally successful Harry Potter is such a perfect fit for TT's famous LEGO treatment. Young people love it because middle class kids go to boarding school to learn magic, and adults love it because, well... we're not sure why, but we know they do because we can see them reading the books on the tube and they don't look at all embarrassed. You know the type: they sigh and roll their eyes as they tell you they're taking their kids to see the new Harry Potter movie, but really they're just as excited to discover who Harry and Hermione get their magic on with as the next sugar-crazed kid.

This is what LEGO Harry Potter: Years 1-4 hopes to emulate: adult and child bonding over LEGO blocks built to look like Harry, Hermione and Ron, in a game world built from the brick up to be broken down, then built up again. It is co-op gaming in perfect harmony; pure, unhindered, unadulterated, unified fun for all the family.

So, what you'd expect to see in a LEGO Harry Potter game based on the first four years of Harry's adventures (Harry Potter and the Philosopher's Stone; Harry Potter and the Chamber of Secrets; Harry Potter and the Prisoner of Azkaban; and Harry Potter and the Goblet of Fire), will be in the LEGO Harry Potter game based on the first four years of Harry's adventures. You'll be able to unlock over 100 characters for use in the classic floaty, two-player co-op, combat/puzzling LEGO style. You'll be able to explore iconic locations from the books and films, such as Diagon Alley, the Forbidden Forest, the village of Hogsmeade and the twisting and turning school of Hogwarts - the biggest single area ever created for a LEGO game and the undisputed jewel in TT's Harry Potter crown. And, of course, the famous Harry Potter story will be told across scores of LEGO-fied cutscenes, packed full of the kind of slapstick, voiceless humour TT is known for.

But - and this is a "but" long-term LEGO fans will consider BIG - what's new? What makes LEGO Harry Potter more than just LEGO Batman, or LEGO Indiana Jones, re-skinned? Appropriately, it's all to do with magic. As you play the game, each of the many characters will learn magic spells, from bog standard zaps that cause LEGO to fall apart in the way LEGO has a habit of doing, to classics like "Wingardium Leviosa", which, as any budding wizard worth his salt knows, is a levitation charm.

Drop-in/drop-out co-op play is, of course, in. The PS3 and 360 versions feature online co-op.

At the start of the game, when Harry's just a wee wizard with a weird lightning scar on his forehead, he can't cast any spells. All he can do is walk and jump about like a frog in a boarding school uniform. But bearded behemoth Hagrid - Harry's companion throughout the early part of the game - can do some magic (despite not being allowed to). So, early puzzles involve moving Harry on to a platform, switching to Hagrid, then casting Wingardium Leviosa to raise the platform, and therefore Harry, to new areas.

Spells are selected via a Mass Effect-style radial wheel. Once it's brought on screen, all you have to do is select the one you want with the thumb stick and away you go. At the beginning of the game all the spells are blacked out. Unlocking them - and filling in the spell silhouettes - as you progress through the story, is one of Harry and co's chief goals.

Free move brick building works on a 2D plane, and is identified by a purple base.

Behaving badly and simply messing about has been part and parcel of the LEGO experience for years now, and so it will be in Harry Potter; indeed the game encourages you to wreak as much havoc as humanly possible. The Transfiguration spell, for example, turns people into frogs and rabbits. Why would you do such a thing? Well, just for the laugh. The people of LEGO Harry Potter don't mind. That's what they're here for. Zapping everything and anything that moves with nary a care for thought or reason is guaranteed to reveal a surprise or two, maybe even a hidden area or a Gryffindor shield (nab four to get a gold brick). You might discover a mini-game, or create your own: causing mischief in the Gryffindor Common Room or bouncing on beds in the dormitories are but two examples.

Structurally, the game follows the traditional LEGO "hub and spoke" system. In this case, Hogwarts acts as the hub from which you progress the story by entering sort of instances. These levels will see you explore some of the more iconic locations from years one to four, and take on some bosses, including the troll from The Philosopher's Stone. But you'll be spending just as much time inside Hogwarts as you will outside of it, doing exactly what you should be doing: learning.

To learn spells, you have to attend lessons, the first of which teaches you Wingardium Leviosa. Following a little cutscene, you're posed a puzzle-based challenge that focuses on the spell in question. Complete it and you'll unlock the spell. Later, you learn to ride a broomstick. This power allows limited flight in a 3D space; you can move up and down like a Harrier Jump Jet, except with less metal and more magic. Hermione, of course, wobbles all over the place. Ron's a bit better, but Harry's the best.

Propping up the virtual halls of Hogwarts, and indeed the many other locations you'll visit, is a brand new physics system which lends LEGO Harry Potter a more tangible, richer feel than previous games in the series. The visual detail is striking: LEGO people walk about in the hustle and bustle of Diagon Alley. The Hogwarts courtyard is packed with students who double as willing test dummies to your magical machinations. In Hogwarts itself, paintings are alive with ghosts, and staircases move about as they do in the films. In Gringotts Wizarding Bank, you can almost smell the money as the goblins go about the business of counting cash. In short, LEGO Harry Potter looks magical.

LEGO Harry Potter is the best-looking LEGO game ever made

Perhaps more important than the graphical improvements, however, is the new brick building mechanic. Here you're able to use magic to move individual LEGO blocks around freely with the left thumb stick, and attach them to each other like actual LEGO. You can then build things, like platforms and bridges, which enable you to reach new areas. Now, it's important to note that this is not a system akin to vehicle-creation in Banjo-Kazooie: Nuts & Bolts, or level creation in LittleBigPlanet. The LEGO building works on a 2D plane, a bit like Tetris, and it's not like you can run around remaking the world as you see fit - TT is keeping things controlled and simple by limiting the building to specific sections of the game. Remember: the LEGO games are aimed at young boys. Brick building isn't quite as exciting as it could be, but it's a start. And the Wii version - predictably - lets you free move LEGO bricks with the Wii Remote as if a wand, which, when you think about it, is pretty cool. But what's not cool? Well, you can't play Quidditch. That's an epic fail right there. But, perhaps making up for it, you will get to use the invisibility cloak, although how it'll be worked into the gameplay we don't know.

So, there's a lot to suggest that LEGO Harry Potter: Years 1-4 is more than just a re-skinned LEGO game. Indeed, it may well turn out to be TT's best game yet. It doesn't look like a revolution by any stretch of the imagination - even one as wild as Harry Potter's - and some of the more headline new features (free-moving LEGO bricks in particular) don't look like they go quite as far as we'd like, but the game looks guaranteed to provide the all-encompassing co-op experience TT has been building for years. And that, really, is the most important thing.

LEGO Harry Potter: Years 1-4 is due out on multiple formats in May.