The game will have a Christmas tree decorated with Christmas presents on the right side of the screen. On the left is a swarm of zombies carrying calculations that are gradually moving to the right with the intention of destroying the Christmas tree (the Christmas tree will have a UI showing the amount of health). Your task is to press one of the buttons with the correct answer calculation displayed on the screen. If the answer is correct, the snowman standing under the pine tree will slide the gift box towards the zombie, the wrong answer will slide (on the zombie will show a new calculation).
* Winning condition: highest score
* Status of loss: Christmas tree destroyed
* How to divide LV:
- Easy: additional calculation, speed and spawn frequency of zombies is getting faster and faster
- Normal: multiply and divide, the speed and frequency of zombies are getting faster and faster
- Difficult: the generality, speed and frequency of zombies are getting faster and faster