So: 2D, shoot in any direction, while moving in any direction. The d-pad obviously controls movement, and because this is a Nintendo DS game, you can choose to use the stylus to direct your fire instead of the fascia buttons. There is no reason to do this, because it just gets in the way of the screen.
The difference: picking up enemy detritus earns power to use one of two mega weapons, which significantly simplify the process of clearing the screen of nasties. And there really are quite a lot of enemies around, released in generally well-timed waves, and from a suitable mix of convenient and inconvenient points in the enclosed levels.
It’s not easy, and its willingness to make you start the entire game again isn’t entirely welcome. But to my mind 2D shooters are expected to be so. No, more annoying are the power-ups, which are unclear and have a habit of being picked up without you noticing. Especially annoying because some of the power-ups are much less useful than others.
Where does all this leave us then? No wiser, but no worse off. It’s looks fine, but not quite as stylish as Geometry Wars. Which just about sums it up.