You can change your nickname in profile section. Here is how it can be done:
- Tap on your nickname in the upper right corner on the main screen in game. You will get to your profile.
- Tap on "Player name".
- Enter your new nickname. Maximum length is 13 characters.
- Press "CONFIRM" button.
IMPORTANT: the first nickname change is free. Second and the following nickname changes would cost 100 gold coins. Choose your nickname wisely before confirmation.