Psst...Picross is better.
An amalgam of "picture" and "crossword," Picross is one of many names for logic puzzles that reveal a picture when solved. Players are confronted by an empty graph; the game is figuring out what squares get filled in. Each line of the graph has numbers indicating how many squares should be filled so if you're looking at a line five squares wide and has "5" next to it, you know every square on that line is going to get filled in.
The challenge comes when there's something less than every square filled in, say, when you have a line ten squares wide and the number given is six, or a four and a three. Now the game becomes a logic problem, as you try to figure out which squares should and shouldn't be filled and slowly put together a whole picture.
Complicated as it might sound, Picross is a breeze to learn. The in-game tutorial spoon-feeds you the basics, then starts you with baby steps: five-by-five graphs with lots of easy fills and simple designs. But after a few of those no-brainers, the game starts ramping up the challenge, and before you know it, you're spending 45 minutes carefully revealing a crude drawing of a rhino.
That might sound like watching paint dry, but proof is in the pudding, and this is scrumptious, choco-raspberry-heroin-surprise-flavored pudding. Most puzzles can be burned through in less than half an hour, so Picross has that "just one more game" quality that will reliably make you late to class, work, bed, your own wedding, etc. There's something about it that's much more rewarding than Sudoku, the game's closest comparison. Whereas Sudoku often forces players into unsatisfying trial-and-error approaches, Picross requires no such wild guessing. You can always identify at least a few squares that must be filled or must be blank. Knowing that tells you about the adjacent squares, then the ones next to those and so on until you've solved it. This puts the pressure on players to make sure their Picross kung fu is righteous, since a mistake early on can snowball until the entire puzzle is hopelessly screwed up.
The game comes loaded with hundreds of puzzles, as well as the ability to make your own and share them over a wireless internet connection so two DS owners can play against each other in a race to solve a puzzle. The "Daily Picross" mode offers an assortment of game variations like "Nonstop Time Attack," where you try to speed-solve five puzzles in a row, or "Error Search," which gives you incorrectly solved puzzles you're asked to fix. Taking a page from Brain Age, Picross records your progress and rewards regular play with new features, so players will get at least a few solid, obsessive weeks out of the game before they've seen it all.
There are niggles, of course. The larger puzzles require the player to "zoom in" to mark them; inexplicably, you can't just stick to the zoomed-out view, which lets you see the entire graph. This forces constant fussing to get a clear look at the areas you're working on, which is a little annoying. But even that isn't enough to diminish what is a near-perfect portable game.