Build 2574229

Hi Everyone
We are excited to share this update:

• New difficulty options
  From the feedback of our players, We noticed that some players thought the game was too hard, while some still wanted more challenges. To meet the requirements of different players, we set 4 difficulty levels for players to choose freely:

  Casual
  Amateur
  Normal(default difficulty in the previous versions)
  Professional

  You could choose the difficulty level when you started a new game.
  For players with saved progress, difficulty level could also be modified in option menu(both at the start scene and during game). The change would take effect immediately!

• Fix a bug that caused game stuck when the game started
• Correct some text errors