The mutated virus triggered a fierce artillery battle. Viruses continue to mutate, and various types of viruses are becoming more and more complex, their individuals are getting larger, and their vitality is becoming more and more tenacious. Intensive artillery fire and an astonishing rate of fire are the only ways to suppress it. The powerful virus requires sufficient firepower coverage to eliminate it. Click the screen to launch cannonballs to attack viruses. Click quickly to fire quickly. Upg