In March, I competed in the American Crossword Puzzle Tournament, a word-game fiesta held every year in Stamford, Conn.

The 2006 tournament also introduced the First American Sudoku Smackdown, a challenge that was greeted with little enthusiasm. I was surprised to find out that many of my fellow crossword addicts had never tried to solve a sudoku puzzle.

I didn't do very well in the Smackdown, but I left Stamford determined to master sudoku. Since then, I've become fairly adept at solving them — and, more importantly, figured out what it takes to make good sudoku software.

The basics: A sudoku puzzle is a 9-by-9 grid that has already been partially filled with numbers. The object is to fill the grid so that all the digits 1 through 9 appear in each row, column and three-by-three block. You don't have to add or multiply the digits; sudoku is a pure logic puzzle. Let's see how the puzzle works as a video games.

4 "Sudoku Gridmaster" (Nintendo, for the Nintendo DS, $19.99): Nintendo has already demonstrated how sudoku can thrive on its portable DS, making the puzzle part of its "Brain Age" mental-exercise software. "Brain Age" has only 100 sudokus, though, so many of us were looking forward to a full-fledged Nintendo game that used the same programming with a lot more puzzles. Alas, "Sudoku Gridmaster" isn't nearly as elegant. Like its predecessor, "Gridmaster" lets you use the DS stylus to write numbers directly on the screen, but the character recognition is less accurate and you'll end up spending more time getting the program to recognize your handwriting while you should be concentrating on the puzzle. At least "Gridmaster" offers an alternate system in which you tap numbers on an on-screen keypad to enter them. And with 400 puzzles, there's plenty to satisfy sudoku fans of all skill levels. Three stars out of four.

4 "Sudoku Mania" (UFO Interactive, for the Nintendo DS, $19.99): Then there's "Sudoku Mania," which seems to do everything its creators could think of to make solving frustrating. For starters, some of the numbers are unreadable. You might think the developers of a game about numbers would care enough to make a "3" distinguishable from an "8"; think again. Here's a tip from the sudoku masters: To solve the tougher puzzles, you need to be able to write more than one number in a box while you're testing solutions. "Sudoku Mania" doesn't allow such a basic technique. Zero stars.

4 "Dr. Sudoku" (Mastiff, for the Game Boy, $19.99): "Dr. Sudoku" was designed for the Game Boy Advance, so it can't take advantage of the DS nifty stylus-and-touch screen interface. Still, it gets the job done within the Game Boy's limitations; you use the A button to enter digits, the B button to erase them, and the left and right shoulder buttons to toggle various features. One of those features lets you select a number and see all the grid spaces where it can't go, which is a big help for less eagle-eyed solvers. And, yes, you can put more than one number in a space. Two-and-a-half stars.