Polarium

This is a puzzle game similar to Tetris in that blocks fall from above, and to clear the lines before the screen fills up, you must create horizontal lines of all the same color (either black or white). To change the color (or "polarity") of a block, you must select it with the stylus, then tap it again to make the block flip. You can also drag the stylus along the screen to change the polarity if many block at the same time.

There is also a puzzle mode where time isn't as critical. Blocks aren't falling, but are just in a certain pattern on the screen. The object is to make the polarity of every block in each horizontal line the same. But the trick is to do the entire screen with one swipe of the stylus. There are 100 puzzles in this mode and they can get very difficult.

The most addicting part of this game is the multiplayer. Utilizing the DS's two screens, you can see your blocks and your opponent's blocks. As you create a horizontal line all of the same polarity, that line is then scrambled and sent to your adversary. The object is to clear your screen before your opponent does. The multiplayer mode does not require 2 Game Cards to play. In fact, when the game is sent over to another DS through the IPL, they don't even need to play multiplayer. The person that received the game can play a simple demo of the game by themselves.