Kakuro \

You might have come across this term while browsing. I tried solving one about a month ago, but left it half-way. But I didn't know it was such a rage before Kaps wrote about it replacing Sudoku in bookstores.

Wikipedia defines Kakuro or Cross Sums thus:

... is a very common type of logic puzzle that is often referred to as a mathematical transliteration of the crossword. In principle, Cross Sums puzzles are integer programming problems, and can be solved using matrix techniques, although they are typically solved by hand.

That itself is enough to drive away a matrix-averse person like me. Hold on, it isn't as nerd-ish as it sounds.

A typical Kakuro puzzle looks like this. The objective is to fill out the white squares (the ones without any numbers or crosses) with numbers from 1 to 9 such that the sum of numbers in the same line as a clue adds up to the clue. That sounds pretty easy, but unless you tinker with a puzzle or two, it is quite tough to get the funda behind this game.

There are a lot many websites where you can try your hand at this new craze. Kakuro.com and Kakuro.net are the top links from Google. It is also a good idea to check out a host of other websites which offer Kakuro games. If you are just starting, do try out the Kakuro tutorial applet and the walkthrough on Kakuro.net.