Portable video games based on the imagination of Walt Disney are nothing new: one of Nintendo’s earliest Game & Watch LCD titles featured the familiar face of Mickey Mouse, for example.

However, as is the case will all licensed properties, there have been just as many stumbles as successes. The sheer volume of failed efforts over the years confirms that capturing that Disney magic isn’t quite as easy as it may seem.

Square Enix seemed to have the formula locked down when it created Kingdom Hearts on the PS2 in 2002. A glorious marriage of typically Japanese spiky-haired heroes and famous Disney faces such as Donald, Goofy, and of course Mickey, this much-loved title went on to establish what has become one of Square Enix’s most popular global franchises.

It's also worth noting that this linage also boasts a proud reputation on portable machines starting way back with the Game Boy Advance release Chain of Memories, and this latest PSP instalment continues that enviable tradition.

Cartoons that come to life

Birth by Sleep is a prequel to the very first Kingdom Hearts title and revolves around three main characters – the youthful Ventus, the brooding Terra, and the feisty Aqua. Fittingly, the game is divided into a trio of stories, each focusing on one of these protagonists.

The storyline is your usual staple of good against evil, but it’s the battle system that appears to have received the lion’s share of development attention this time around.

Combat occurs in real-time, with attacks stringing together combos which can be augmented by special commands. As you progress you’ll unlock further commands, which can be assembled like a deck of cards.

Although encounters with enemy units initially seem to be little more than button-mashing affairs, the system reveals its complexity later on in the adventure, when you start to factor in unique d-Link attacks (which call upon characters from the Disney universe) and intense finishing moves.

The only fly in the ointment is that things become so chaotic at times that targeting the correct enemy becomes unnecessarily frustrating.

Visually, Birth by Sleep is a real treat. The characters are lushly animated, looking as if they’ve stepped directly out of one of Walt’s famous cinematic masterpieces. Backgrounds are a little sparser, but the themed levels – which take inspiration from famous Disney flicks – are instantly recognisable and appealing.

Don’t keep me waiting

While the battle mechanics and graphics are unquestionably polished, their impact is hindered by the atrocious loading times. Birth by Sleep isn’t the first game to fall foul of Sony’s decision to use optical media as storage for the PSP console, but here the intrusion seems particularly obnoxious.

Birth by Sleep is tremendously heavy on non-interactive cut-scenes, and sometimes you’ll have to endure multiple load times during these moments of exposition. We’ve said it before and we’ll say it again: loading times and portable consoles do not a happy combination make.

Having said that, we're sure that hardcore fans will no doubt be able to overlook this issue, as well as Birth by Sleep's other minor problems.

In terms of what it brings to the Kingdom Hearts story, Birth by Sleep is incredibly significant. It could be argued that Square Enix still hasn’t quite succeeded in fusing together its own creations and those of Disney himself, but Birth by Sleep nevertheless manages to stand out as a notable action RPG, and another reason to postpone the oft-predicted death of the PSP.