There are 2 game modes to be chosen, Standard mode and Classic mode, which you can choose on Settings-Game mode.
You have 3 HPs in each level, which will be deducted when you make mistakes, 1 point per time. If you solve the puzzle before all points are deducted, the level is completed. Otherwise, the game is over.
Advantages: this mode suits new players. They can know the answer is right or not immediately and solve the puzzles easily.
Similar to the traditional puzzle book, the level is completed only when all the fill-in are correct. No hint appears when you are wrong.
Advantages: this mode suits users who are more skillful. It is more challenging and brings users a sense of accomplishment. No HPs here.