Hi Dmitriy,
Welcome to our community! 
Whether you call NextGuess in StartGame is a design decision. From a human perspective, does it make sense to class NextGuess if there hasn’t been any initial guess yet? For the computer, our method names are completely meaningless but we also have to keep the people in mind who might read our code and try to understand it.
See also:
- Forum User Guides : How to mark a topic as solved