It's name is Picross DS. The game is probably best described as Sudoku mixed with Connect-the-Dots. It's basically acollection of these puzzles, which are apparently called nonograms, that in order to solve you must use the process of elimination and basic logic. I got the game about 2 days ago and I play it at almost every oppurtunity I get. I'm going to submit a review sometime this week, and I'd recommend it to anyone who's interested in a puzzle game for their DS.

*UPDATE*
I didn't get around to writing that review this weekend like I had planned (There goes my procrastination again :P) HOWEVER it will be the very next review that I submit, whenever that may be.