The original Sonic the Hedgehog (1991) for the Sega Genesis managed to bring a totally original take to the platformer. Mario had two speeds: a slow walk and a run that was a bit faster. Sonic, on the other hand, blazed through levels, going through all manner of crazy loop-de-loops and obstacles.
In the intervening years, not a whole lot has been done to mess with the formula (besides the inevitable and disappointing transition into 3D and a couple of spin-offs). So it should come as no surprise that the first Sonic game on the DS follows the same pattern: a minimum of changes to adapt to a new platform. In this latest installment, Sonic barrels forward at full speed through two screens... exit one and you enter the other. I'll admit that this is a clever use of screen real estate, but with the split-second you're in limbo between the screens it can leave you disoriented.
I'd also like to take a moment to rant about the plot, because I found it to be more or less completely irrelevant - some vague notion about traveling between separate dimensions to foil (yet another) plot by the series-standby Eggman. You'll probably end up asking yourself the same question I did: why did they even bother having a story? If the plot has any purpose at all, it's to introduce Blaze the Cat, newest addition to the Sonic roster. Blaze plays pretty similar to Sonic, other than the flaming tracks she leaves behind.
The boss fights are a change of pace from the rest of the game, since they're in true 3D. They all require different tactics, which keeps things interesting. But, other than that, the rest of the game play lives up to the title, and, if anything, Sonic rushes through everything a bit too fast, with no real time to choose between branching paths in levels.
As you progress through a level, a gauge fills which allows you to perform a charge move that takes you straight through enemies, meaning there's no slowing down even to fight (aside from sequences when you have to destroy a certain number of enemies to move on). Other than that, classic Sonic through and through — but at this point, the formula doesn't feel as exciting as it once did.
Sonic Rush is rated E (Everyone) by the ESRB for Mild Cartoon Violence.