The puzzle is based on the old SMS text messages, used in the days before smart phones.
In those days, you had to select each letter in your message by repeatedly pressing a number key
 
The computer is thinking of a 5, 7 or 9 letter word. (It is a normal English word, not obscure and no accents/hyphens etc.
The word is made up using 1 letter from each column of buttons
Click on any button to place a letter into your guess
Win the game by completing the correct word.
Don't worry about mistakes, clicking any letter button will overwrite the corresponding letter in your guess