A superb beat-matching game, Groove Coaster is Infinity Gene director Reisuke Ishida's latest project. Levels are songs, and as they play your avatar progresses along a twisting line. Tap the screen when it passes over the beats, and enjoy the progression of the track. Timing is rewarded with a "cool" or "great!" rating, and chaining together beats without misses is the route to higher scores. Beats take different forms: some require directional swipes rather than taps, others holding down for a certain time. The variety means you're always kept on your toes, and it can make harder difficulties a genuine challenge.
The levels themselves are often a visual spectacle. Matched beats are accompanied by an eye-catching splash of colour, and as the tune progresses the level twists and turns at speed, fully fitting its 'coaster title. A wireframe style gives the game a wonderful retro feel, especially evident when playing through some of the Space Invaders and Araknoid remixes. It all feels incredibly dynamic, and as faster levels bounce you round corners and twist up through crescendos you'll be engrossed with the concentration required to keep up.
The wide variety of tracks included in Groove Coaster are the icing on the cake. At the moment there are 27 available, some through unlocking and others to be bought as downloadable content. It's proof of the addictive quality of the game that you'll find yourself eager to buy more tracks, just so you can see how good they are. The tunes are decidedly electronic-influenced, but there's enough variety to keep most people happy. You can guarantee that at least some will be stuck in your head for days afterwards.
Groove Coaster's high placing on this list is based on the fact that I just can't stop playing it. Probably a bad characteristic for an iPhone game to be honest; I find myself trying to squeeze in a level or two almost everywhere. It reminds me a little of Rez. Not only in the fact that I won't shut up about how brilliant it is, but because of the superb soundtrack, stylish wireframe visuals, rhythmic gameplay, and maddeningly addictive qualities. If you're an iPhone owner, it's an absolute must.