Codeword Unlimited is an application to play the popular word game known as Codeword (also known as Cipher crosswords or Cyptograms).
The words to find are in English, or you can play in 35 other languages.

For those unfamiliar with Codeword puzzles, they provide a grid of words, similar to a normal crossword, but with no clues, rather a few initially provided letters, and a number in each square in the gird to indicate its (as yet unknown) letter. All boxes with the same number must use the same letter. From that information and the few initially provided letters it is possible to work out which words will fit in the boxes. Hence you are decoding (or decyphering) the numbers into letters to reveal the hidden words. Usually all 26 letters of the alphabet are used in the codeword, although not always (and unused letters appear crossed out in the keyboard). It is fun, challenging, and a real brain teaser.