The physical issues are a shame, because the heart and soul of GH remains vaguely intact for some of the single-player game. The career mode is a 'lite' version of GHIII's, offering your band the chance to play gigs in a range of slightly odd locations, ranging from a rooftop to a carnival float to a battleship. It's not as witty or Spinal Tap-ish as GHIII, but it works. Two new characters join four existing GH favourites in the roster of heroes and heroines, while the range of unlockable guitars covers a reasonable range of Gibson classics and rarities, and you can actually see your axe of choice on the touchscreen as you play.
Basic gameplay works in much the same way as it did in GHIII, but with a couple of tweaks for the DS. With no physical whammy bar to play with, you now have to bend notes and add vibrato by scrubbing the virtual bar on the screen. That old Star Power boost, meanwhile, is now activated by shouting 'Rock Out!' into the microphone or - if you're on the train and keen to avoid weird looks - tapping the relevant gauge. This can cause problems if you hit it during an overenthusiastic bout of strumming.
While the right/bottom screen is busy with this lot, the left/top screen shows the usual scrolling tablature display along with 3D performance footage in the background. Understandably the visuals aren't quite as slick as they are in the mainstream console versions, but they're not a bad facsimile at all. Sound quality is also surprisingly good. Obviously some compression has been needed to get 25 songs on a DS cartridge, but put some headphones on and there's still enough 'rawk' for the average metal monster.
On easy level, GH: OT is simple, fun and accessible. On medium level it's thoroughly enjoyable and a decent starter challenge even for the intermediate GH player. On anything above medium level, things start to go awry. I'm not sure whether it's the cramped layout of the buttons on the grip or the limitations of the touchscreen, but pulling off any fast or complex sequence of notes is a nightmare. Scrubbing the screen doesn't work for fast picking, and some long sequences of repetitive notes seem more a test of luck than rhythm.