Geometry Wars Galaxies for the DS provides a great port of the classic XBL Arcade game for your on-the-go needs.
Galaxies has two primary modes: Galaxies, and Retro Evolved. Galaxies is an all new single player mode, while Retro Evolved is a port of the game from Xbox Live Arcade. In Galaxies mode, the player is shown a Galaxy select screen, and can initially only visit on location. There, each "Planet" represents a specific challenge to overcome. I have yet to unlock them all, but so far they have been nicely varied (However, the color of the planet indicates a similar theme.) with even simple things such as the level (Being an Octagon instead of a Rectangle, for example) design creating new ways to think and play the game. The game play itself is solid, though due to a lack of analogue sticks, the play is allowed to either press the buttons (For a right) in any combination to shoot any of eight directions. Or, they can use the stylus and touch screen to aim around in a reticule on the bottom screen. While this is a bit limiting, having such few directions to aim with, the programmers must've for seen this problem, and I've noticed enemies tend to be a bit more linear with their attack patterns.
Also included in Galaxies mode is the concept of a helper bit, which is a small polygon that follows you around and assists with attacking the enemies. There are several "AIs" you can unlock, and they level up as you use them, allowing for smarter aiming/movement and better firepower.
As of righting this review, I am only a few systems into the game (Less then half unlocked.) You start off with only one, but as you beat the missions, you earn points called "Geoms" that you can use to buy new AIs, unlock new missions, and then unlock new galaxies. Each Mission carries with it a target score to reach a medal, ranging from Bronze, Silver, and Gold, which when achieved grant a generous amount of Geoms, so the incentive to hit these markers is fairly high.
Overall, while this game does feel much slower and easier then the XBL Arcade versions, it has a few features I find make a good twist on the game, and the actual game play is still solid, boasting great visuals (For the DS) and a solid musical score. If you are itching for some Geometry Wars to take on the go, I strongly recommend this game. If you are a big fan of the series such as I am, I would again highly recommend it. I picked up my copy new for 20 bucks, and it was well worth the price.