We've had Guitar Hero on the DS, complete with odd add-on peripheral, but until now Rock Band has remained a home console game only. Portable gamers wanting a Rock Band fix while out and about need fret no more, though, as Rock Band Unplugged brings the band experience to the PSP - and there's no awkward peripheral in sight. It might sound like a recipe for a dull, uninspired game, but Unplugged is easily one of the best PSP games of 2009.

Central to Unplugged is the Tour mode. Fans of home console Rock Band will know roughly what to expect here, but for those coming to the game as complete novices it's your typical story of a struggling band trying to make a name for itself. After picking your band name, motif and hometown you get to choose your four band members and customise them slightly. Once that's done you're ready to start playing gigs, small at first, but eventually once you've gained a strong fanbase and enough stars you'll be playing massive sell out gigs and touring big cities.

That's more or less the idea behind the game, with a bit of mild band management thrown in too, but the core gameplay is how you play the tracks that are going to make you famous. The notes scrolling down the screen mechanic that we've seen in Rock Band and Guitar Hero is present here, although there are a few noticeable changes to the standard formula. The big difference for many is the reduction in fret buttons from five to four, and that you're hitting buttons on the PSP rather than those on a fake plastic guitar.

While this might sound like a complete deal breaker, considering much of Rock Band's success stems from the feeling of being in a band and actually playing an instrument, it works surprisingly well. The four buttons are mapped to left and up on the d-pad and square and triangle, which works well and we really can't think of a better solution. It will take some time for your brain to work in tandem with your fingers as the notes stream down the screen, but after a few hours your fingers will be moving around almost on autopilot.

So that's how you strum, but this is a band game and you've only got one PSP to play all the instruments on. This is handled by having a separate track for vocals, lead guitar, bass and drums and making you hop between them as each song progresses. If you successfully play an entire set of notes on one instrument track you can press L or R to switch to another, picking up the tune with another instrument, doing the same and then moving on again. It makes for some frenetic button pressing and most likely uses parts of your brain that you didn't know existed.

Add in the usual score multiplier mechanic that builds as you continue to hit notes without missing, the overdrive move that doubles that multiplier and instrument solos and there's a complete Rock Band experience here, albeit with a slight twist to make it work on Sony's handheld. On top of the Tour mode there's the expected training and quickplay modes, a band survival mode and the option to play just a single instrument throughout an entire song.

The gameplay becomes highly addictive

If there's a criticism to be levelled at the game it's the complete lack of multiplayer. The game is built around playing all four instrument types together, switching between them throughout, so a multiplayer mode would have changed things considerably, but even some basic form of band play with four players would have been better than nothing. There's also considerably fewer tracks on offer here than in the home console versions of the game, with just over 40 included on the UMD. Add to that the fact that there's an in-built music store, suggesting more tracks were ready for launch, and some players might feel a little short changed.

Rock Band on PSP doesn't quite have the visual flair of the home console versions, but everything looks pretty great on the handheld's sharp display. Most of the time you'll be too focused on the notes to pay much attention to the background, the band members look decent and there's good use of filters to give the stage performances a stylish appearance. The sound quality is also very good, but it's essential you use headphones and not the PSP's in-built speakers.

Those expecting Rock Band Unplugged to be a poor imitation of the big daddy versions might be in for a shock. Unplugged manages to bring the band experience to the PSP in a way that works for the system and is highly addictive to boot. The lack of multiplayer is disappointing and we'd have preferred a few more tracks, but for finger tapping fun on the move this comes highly recommended.