Did you hear that guitar games are in fashion now? As Activision try their absolute hardest to milk their cash cow Guitar Hero series so dry that the poor bovine dehydrates, Harmonix and MTV have been comparatively restrained with the Rock Band franchise, with only two full games in the series so far, and only now getting their first handheld entry out in the open. Surprisingly it wasn't pitched on the DS to rival Guitar Hero: On Tour - the patchy handheld iteration of Activision's rhythm music piggy bank - but instead for the most-developers-wouldn't-write-for-it-if-you-paid-them PSP.

Of course, Guitar Hero got around the problem of not having a massive guitar attachment by adding a fret-board plug-in for the DS's (and not DSi's, notably) underused Game Boy Advance slot, but thankfully Harmonix hasn't attempted to crudely force a similar slot in the UMD drive, instead opting for a far simpler solution: all four buttons are on the d-pad or face buttons. But perhaps I'm going a little too fast for those who managed to miss the fashion for sporting oversized plastic instruments and strumming wildly away at the TV screen. The original Guitar Hero for PS2 - back when the series looked to be going the same way as Samba De Amigo on the Dreamcast, namely an expensive novelty collectors' item - saw you pressing brightly coloured frets on a large, plastic, guitar-shaped controller in time to the notes scrolling down the screen as a rock hit played. If you screwed up, the fans would throw things at you in the time-honoured fashion of those discontented at gigs, while they would applaud your brilliance when you succeeded. It was a great formula.

Some years later, Harmonix left Activision to build Rock Band with MTV, leaving their former publisher to continue the franchise with something missing. Rock Band was Guitar Hero+. It allowed not just a guitarist to play, but a drummer, singer and bassist too - a sort of unholy lovechild of SingStar, Guitar Hero and Donkey Konga. It was ace and we all loved it. Then Activision played 'me too' with Guitar Hero: World Tour and boasted better quality instruments but - in my opinion - a weaker gaming experience. In some ways therefore, it feels a bit of a step back to go from a room full of brightly coloured instruments to just a screen and your fingers again. In fact though, this is more a case of Harmonix going back to their routes - they had a couple of games called Amplitude and FreQuency for the PS2, and Rock Band Unplugged feels closer to this than a fully grown Rock Band experience.

IN Rock Band Unplugged then, you use the left, up, triangle and circle buttons on your PSP to match four notes on each section. To keep the track playing, you have to switch between instruments using the shoulder buttons to ensure that none of them go into the red. By chaining together combos, you not only hear the song in its entirety but you can also chase the kind of high scores that felt compulsive in the rhythm action games of old. Maybe it's just me, but the Guitar Hero/Rock Band games never made me a high score chaser; I was just happy to finish the tracks when I sucked and to get five stars now I've gotten decent. Unplugged, on the other hand, compulsively makes you chase the high scores by chaining together runs and using 'overdrive' at just the right time. Overdrive, to the uninitiated, is Rock Band's equivalent of 'star power' and allows you to recover 'failed' instruments as well as doubling your multiplier for a limited time.

Of course, a game like this lives and dies on its track list, and it's pleasing to note that it's a popular greatest hits set from both Rock Band catalogues; ABC by The Jackson 5, Today by Smashing Pumpkins, More Than A Feeling by Boston and Bon Jovi's Livin' on a Prayer make up the early tracks, while the likes of System of a Down and Judas Priest make up the finger-numbing difficult tracks later on. While the audio feels a little tinny through the PSP's inbuilt speakers, using headphones reveals a very high sound quality that makes jamming through the tracks a complete joy - and there are forty-one in total, with more available to download for a price. It's shame that those already tied into paying for Rock Band DLC elsewhere can't be given this for free - I appreciate that would be tricky for 360 gamers, but surely the PS3-PSP interactivity could make this possible and avoid the slight feeling of being ripped off felt by those who find themselves paying for the same songs on different formats, but the core forty-one is still a decent number to keep you rocking for a while.

Graphically, Unplugged it quite a looker; with Rock Band available on PS2 it was simply a case of scaling down the graphics - and on the small, bright screen it works to great effect. You most likely won't notice your band avatars' crazed antics when you're in full concentration mode nailing a tricky solo, but they do look pretty damned impressive. The core notation charts are very clear and you can't blame a perceived delay between the sound and the note as you potentially could with some TVs on the console versions - this one is pretty much spot on.

If you do manage to draw your eyes away from the notation charts and risk fluffing the song in the process, you'll see your colourful rock avatars jamming along to the music. The customisation options are all present and correct from the console versions, allowing you to create all four band members and get them new clothing and instruments as you go. It's all cosmetic and it's arguable that on a smaller screen this is even more superficial than on the console versions, but it goes a long way to soothing the doubts of those who worry they're getting into a whole different ball game. In fact, the only complaint I can possibly muster about Unplugged is the absence of multiplayer, which is odd, because the PSP has wireless options available and Amplitude managed online play fine, even on the ancient PS2, yet it's been skipped over here. This is a pity, but perhaps this more introverted version of the game is better suited to a handheld anyway - leave the competition and banter to the larger console version.

Rock Band Unplugged is very different from its full grown console brethren, but still a highly engaging portable game in its own right. It's almost a different way of enjoying music on the go, and for those who have gotten too accomplished at Guiter Hero/Rock Band to enjoy it, this handheld version makes you start from scratch and get that stinging sense of incompetence all over again. For those about to rock, I salute you, but please for the same of London Underground, use headphones if you're commuting near me.

Reviewed by Alan Martin for AceGamez (All Rights Reserved).