You will be given a clue, like 'friendly peacock'.
This is a bit like a crossword clue, but the answer is always a pair of words, and the two words are the same, except for one letter (they're off by one).
Naturally, the two words are the same length.
You can get a series of hints by clicking the 'Hint' button.
For example, the answer to the above clue is made of words with 8 letters.
The first letter is 'P', the second is different, and so on.