The defense tower gets corresponding bonuses at different time periods according to its own five element attributes. Players get the corresponding yin and yang attribute bonuses to act on the defense tower during the day or night according to the selected yin and yang attributes, and the bonus value is different in different time periods. Waves of monsters hit the player's castle, and the castle uses rune technology to increase its own HP and various attribute bonuses of defense towers. If the castle is broken, all the defensive towers on the map will be destroyed and restart the game. The level of the defensive towers placed on the map is fixed. After the defensive towers are upgraded, the already placed defensive towers will not be upgraded.