update for version 1.21.8 — Tank Guards Steam update #572968

1. Slightly reduce the explosion range of enemy explosive vehicles 2. 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 3. 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 4. The fire speed of the player's gu...