update for version 1.21.8

Slightly reduce the explosion range of enemy explosive vehicles

Add sound effects to enhance the game experience a. Add the sound effects of fire, water, electricity, mines and rockets, and no longer use the same sound effects of bullets before. b. Add the sound effect when bullets collide with the map boundary, and no longer use the same sound effect of hitting the tank

When replacing the gun barrel, the gun barrel level retains the original gun barrel level and no longer starts from 0 to better adapt to the rhythm of the leisure. Players can purchase factory props to upgrade the gun barrel when replacing the gun barrel. In addition, the props of the additional barrel upgrade series (the additional upgrade is obtained from 0 when converting the barrel) are modified to upgrade directly from the original barrel level when converting the barrel

The fire speed of the player's gun barrel is greatly increased, but the ability to counteract bullets is greatly reduced, making the gun barrel more characteristic

The movement speed of the enemy is only affected by the type of body, and the bullet power is only related to the barrel before. Instead, different combinations of body type and barrel jointly affect the movement speed and bullet power, making the enemy more different and richer experience