Oh, I see from the recycle bin that Red guessed without offering a letter.
Just to explain why that rule is there: If you guess at the answer but do not include a letter guess, it causes a problem if you happen to be wrong. It does so because there should be another stage of the gallows as the guess was wrong, but with no letter added to the "used" section it is unfair on other players.
Another reason is that in the original game of hangman, you were only entitled to guess at the answer when you had guessed a letter correctly. In this case offering a letter along with the guess is in line with that original rule, and if the letter is wrong then the subsequent guess would also be, and therefore the guess is invalid anyhow.