I'm sure you're all familiar with the guitar hero formula by now. Even if you don't own a copy yourself, Guitar Hero and its progeny, Rock Band, have so permeated the social consciousness that nearly everyone at one point or another has strummed that plastic guitar. Even Guitar Hero tournaments at the local pub are the norm near my house. With millions upon millions of gamers and non-gamers alike currently riding the Guitar Hero bandwagon, it was only a matter of time until Activision was able to marry the popular franchise with the world's most popular handheld, the DS. While you won't be carrying a plastic guitar with you on the bus, On Tour: Decades is a fun rhythm game that simulates the act of playing guitar hero, although the actual guitar simulation has been left far behind.

Fundamentally speaking, On Tour: Decades plays the same as the home versions. You're still holding down fret buttons and strumming notes as they come towards you on a constantly moving track. GHOTD utilizes a "guitar grip" peripheral, which provides four fret buttons (orange has been left out because sliding your hand would be impossible on the DS). The device attaches into the Game Boy Advance port on the DS, and uses a Velcro strap to hold the unit in place on your hand. Strumming is done by sliding the stylus or included guitar pick back and forth over the touch screen. The grip works on both the fat and Lite DS models, but all you DSi owners are fresh out of luck. The game provides a decent portable approximation, and certainly tests your rhythmical skill much like the home console versions. Just make sure you keep your wrist as straight as possible and find a comfortable position to play in, lest your wrist feel like it's had a Gibson X-plorer smashed across it by an over zealous heavy metal rocker.

The other danger this game provides is looking silly in public. One of the first things my girlfriend said to me when my review copy arrived was something along the lines of: "There's no way I'm going to be seen in public with you when you're playing with that… thing." Funny, I think more people are concerned with the homeless guy with the "enchanting musk" sitting in the back corner of the bus trying to eat his own hand. I suppose if Boxcar Joe isn't around trying to snack on his undoubtedly barbecue flavoured appendage, then you might get a few odd glances your way while playing GHOTD on public transit.

Public ridicule aside, GHOTD proves to be a whole lot of musical, portable fun, and it all begins with the game's outstanding soundtrack. The game progresses through tiers each one representing a different decade in rock. The game begins in the modern era with radio friendly ditties like "Pretender" by the Foo Fighters and "Dirty Little Secret" by the All-American Rejects. As the player rocks their way back in time, they'll be treated to some awesome milestones of pop and rock like "Buddy Holly" by Weezer, "No Rain" by Blind Melon, "La Bamba" by Los Lobos, "I Can't Drive 55" by Sammy Hagar, "Free Ride" by the Edgar Wright Band, and a live version of "Sweet Home Alabama" by Lynyrd Skynyrd. There are another two dozen or so tracks, including a few unlockable ones. There are surprisingly few duds on the game, and I would go as far to say that GHOTD has the best ratio of studs to duds of any music game to date.

To help increase replay value, players are given three options at the outset of a new career mode: Lead guitar, bass, and guitar duel. The first two are pretty much exactly as they sound, having players go through the track list as the aforementioned instruments, strumming notes as they come towards you on a musical track. The guitar duel mode is an offshoot of the boss battles that were prevalent in Guitar Hero III. Personally, I thought these duels completely ruined GH III, and they're no more welcome in my portable rendition. I just don't see any fun in avoiding bomb notes, fixing guitar strings and signing autographs when I just want the rock out to "We are the Champions." For those who like these duels (and I can't conceive why), there's a few clever twists on the formula made possible by the touch screen.

Also, there are several multiplayer modes, including the aforementioned guitar duels, and co-operative modes. In a nice touch, owners of the original On Tour can play with Decades owners, and songs can be shared between the two versions. Still, the only thing goofier than one person playing guitar hero on the bus, are two people playing together in the same setting.

As you progress through the game, you'll unlock loads of new clothes, guitars, and extra songs. Certain items can only be unlocked by achieving certain criteria, such as beating the game on hard or getting a 250 note streak.

Where the game suffers, is its reliance on the touch screen technology, particularly when it comes to expert mode. The touch screen doesn't offer any feedback like the clicking strum bar on the home version, and it renders the expert mode nearly unplayable. You can never tell if you're missing notes because of your off rhythm, or strumming the wrong part of the screen. During particularly note intensive songs, the touch screen simply cannot keep up with the intense strumming either, as every strum means making contact again with the touch screen. You can't simply leave the stylus on the screen and strum up and down. This means that playing nearly any song on expert will result in the bus driver receiving a flying DS in the back of the head. On the plus side, I was able to beat every song on hard on my first try, so only the expert difficulty mode is pretty much broken.

Another gripe I had with GHOTD is the baffling graphical layout. The top screen is only occupied by the note track and the pixelated graphics of your band playing. The band isn't terribly well animated, and there's no synchronization of the visuals and the song you're playing. Milli Vanilli would be proud. Furthermore, all your information is on the touch screen. Considering how much focus and retinal energy is required to keep up with the oncoming notes, all your other information might as well be on your TV at home. Things like star power (activated by touching the meter or blowing into the DS mic), your score, and most importantly, your rock meter are all on the touch screen that at best will get a cursory glance during slow passages. It's unfortunate that everything is so tightly packed on the touch screen, while the top screen reeks of wasted real estate.

Audio, on the other hand, is excellent. While you'll want to play the game with headphones, you'll experience a shocking amount of clarity and fidelity using the standard DS speakers. While it negatively affects gameplay, the lack of a clicking sound from the controller means freedom to hear the song in its entirety. Best of all, there are no covers to be found here, as all the songs included are master recordings from the original artists.

Just remember, while Guitar Hero was all about simulating the act of playing a guitar, GHOTD has no such aspirations. This game's only goal is to simulate the act of playing Guitar Hero, nothing more and nothing less. With that said, GHOTD is a fine addition to any Guitar Hero fan's library, especially those who want to take their fix on the go. While a few nitpicking issues ruin the expert mode and make the package far from a five star effort, Guitar Hero remains a very fun experience, even in a stripped down portable form.