When a work has an excellent premise, it's always interesting to find variations on the theme. Haydn knew it. Beethoven knew it. Now Conceptis gets on board with another in their popular series of browser versions of pen-and-paper puzzles, and this time the focus is on perhaps the most popular remix of that ongoing phenom, Sudoku. Chain Sudoku Light Volume 1, designed with the same care as its fellow works, is a twisty variant that's very, very good.

Battle 60 new levels of Sudoku in this next installment of the Conceptis Light series of puzzle games. Offering up the same mixture of Sudoku puzzles from Mix Sudoku Light Vol. 1, only harder, this set of puzzles is not for the Sudoku novice or easily frustrated. If you're looking for a decent challenge that's the perfect length for a little break, solve a puzzle from Mix Sudoku Light Vol. 2!

Described by its creators as "MacHeist to go", The Heist is a brand new iPhone release that packs four types of puzzles together in a thrill-filled world where you play a spy trying to crack open a safe. From the fake phone calls, the heavily-secured steel door in front of you, and the real prize waiting for you at the end, The Heist is a challenging collection of puzzles that pulls you in with flawless execution.

Sudoku fans should rejoice with this new release from Conceptis. It contains a number of classic puzzles, along with several variations including Diagonal, Irregular, Chain, Odd/Even, and Multi. The sixty puzzles are over far too soon, but with such a well-done interface, the next volume is eagerly awaited.

Got a hankering for some logic puzzles? Ideas Pad has your fix with Puzzler World, a collection of over 1,200 puzzles ranging from crossword to sudoku to Link-a-Pix. Featuring a big, friendly interface and a straightforward setup, Puzzler World lets you jump right into the games without having to fuss with anything. It's just pure puzzles and a whole lot of head scratching.

Researchers agree: playing logic puzzles requires your brain. Exactly what's required of it, they can't seem to agree, but it's the general consensus that the net effect is positive. Enter Strimko, a sudoku-like game of logic that involves placing numbers on a grid. Instead of a dry, angular box, however, you get to work with number chains that snake their way around the grid, adding a nice, flavorful twist to the familiar concept.

Conceptis offers a variety of logical challenges at its website available to anyone. Eleven different puzzles await the intrepid solver, including familiar puzzles like Sudoku, Picross (here called "Pic-a-Pix"), Kakuro, Slitherlink, and a variety of puzzles that might even be new to logic puzzle lovers.

Sudoku Craving is a great resource for sudoku addicts looking for their daily logic fix. The interface is clean and elegant and, in addition to keeping track of your personal performance on each puzzle, comment boards and high score charts encourage community participation and competition.

Sudoku Combat is a browser-based multiplayer version of the popular puzzle game that offers a new experience for those that prefer a more competitive challenge. Just enter a user name, select a puzzle difficulty, and then choose to play against a friend or a random stranger. Then it's a race to the finish.

Sudoku is a popular puzzle game that began in Japan and has subsequently spread like a wild fire throughout the rest of the world. Similar in form to a crossword puzzle, the game is played using numbers only. There is no math involved, just the correct placement of the digits into every row, every column, and 3x3 square. Web Sudoku provides your daily puzzle fix conveniently over the Web.