Why do we need to return anything in the promptForGuess method?

I don't expect this to be the best reply or it might not even be helpful at all, but as far as I understand it the case is as follows.

The promptForGuess method should be returning the mGame member variable with the method applyGuess and a parameter of guess as seen below . This is necessary to obtain the character input by the user.

public boolean promptForGuess() {
        Console console = System.console();
        String guessAsString = console.readLine("Enter a letter:  ");
        char guess = guessAsString.charAt(0);
        return mGame.applyGuess(guess);
    }

The purpose of the boolean expression within the applyGuess method...

public boolean applyGuess(char letter) {
        boolean isHit = mAnswer.indexOf(letter) >= 0;
        if (isHit) {
            mHits += letter;
        } else {
            mMisses += letter;
        }
        return isHit;
    }

... is to determine whether a given character is hit or a miss - this is best and most simply expressed as a yes or no, a 1 or a 0 and so a boolean return value is important in the game's functionality. Although the code might still run, the boolean return value will allow the program to assess and subsequently score the user.

the code has been updated in the video "valudation"

glad i could help