The Boggle Master reference article from the English Wikipedia on 24-Apr-2004
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Boggle Master

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Boggle Master is a modification of the original crossword game Boggle. The only difference in this edition is that the grid of letters is 5x5 instead of the more traditional 4x4.

Because so many more words are possible, Boggle Master is sometimes played by only allowing 4-letter words or higher. Some hardcore players have set the limit at 5-letters.