2. You must now come up with a valid 4-letter word that differs by exactly one letter. For example, if the computer's word is "TAIL", you can play "TALL" or "FAIL" but not "CALL".
3. The computer responds under the same rules. So TAIL → TALL → TALK → TASK → CASK → CASH → DASH is a valid sequence.
4. Each word is scored - Scrabble style - and a running tally is kept.
5. The game ends when either you are ahead by at least 5 points or the computer is ahead by at least 10 points.
6. The computer might come up with an unparliamentary word every now and then. It's a 4-letter word game after all! Have fun!