As any of the roughly six zillion books filled with the griddy number puzzles would attest, it's pretty tough to muck up sudoku. One of the reasons this type of mind-bender has literally swept the world by storm - at least the portion that still does word searches and crosswords and cryptograms - is that it's conceptually simple and immediately accessible. You have a 9x9 grid. You have some numbers. And you have to fill in the rest of the numbers so that every column, row, and smaller, 3x3 sub-grid contains the digits 1-9 with no repeats. No math or trivia knowledge required; just logic. That's all there is to it.
Above: What visual clutter? By the way, the little baseball heads in the way is what happens in multiplayer or boss battles.
It's tough to screw up, but your first reaction upon setting eyes upon Toon-Doku is that someone tried to do exactly that: tried really, really hard, in fact. It's mostly the fault of the tiny, fuzzy DS screen. It's one thing to have to make out numbers, but easily discerning a pie from a taco from a pizza from spaghetti can get really tricky. Sometimes, they even toss some busy wallpaper behind the transparent playfield, enabling the background to interfere with the symbols. To be fair, you can double-click a shoulder button to zoom in on one 3x3 grid at a time, but we found that view was actually too constricted - we were constantly forced to either scoot the grid around by hand or zoom back out and select a different area to magnify - neither of which were fun solutions.
Luckily, there are two ways to make things better. As you complete puzzles, you can unlock new pictures to replace the ones that give you the most trouble. For instance, there are numbers in your image collection right at the start, so you can just swap those in to make these into normal sudoku. Or, you can do what we did and try to use nine different colors: lemons, grapes, cherries, a garlic clove, the Mona Lisa, a blue-haired anime girl's face... that sort of thing. You can make and trade your own pics, too.
Above: Forget all you know! In Toon-Doku, "9" is the number before "Corn"
Once you get the hang of the images, there's a clunky interface to contend with that makes you drag and drop images (why can't we just tap on the boxes?), and that sometimes just won't acknowledge that you're trying to select a single box to view it's grid of possibilities, and which has a cumbersome way of letting you make notes in the boxes about which pieces might fit there once you've selected it. This might sound nit-picky, but sudoku players will confirm that these are fundamental tools that just don't work properly. But this is, ultimately, still sudoku, which you either like or you don't.
As for how many puzzles there are, it's tough to be sure - there are 110 in the "story" mode, but there could be different ones in the quick play mode - it's difficult to tell. It still seems a far cry from the 400+ in Nintendo's own Gridmaster. Finally, there's a versus mode in which you race against an opponent (ad hoc) or the CPU for those who aren't satisfied with just giving the timer a beat down. Overall, Toon-Doku is a fair package for puzzle fans, but don't think for a minute that gamers who don't already dig sudoku are going to play this and join the numbers in boxes movement.