==================== Bull Cow Game 2.0 ====================

Bull Cow Game 1.0 source: https://github.com/UnrealCourse/02_BullCowGame

New features:

1. Provide a game helper to explain the rules.
2. Users can decide what length of word they want to guess.
3. The hidden isogram is generated randomly each time.
4. Users can choose to play with the same hidden isogram or a new word, but if the game is won, users can only play with a new word.