Welcome to the Rambo Hit Em Up field. The conflict starts against the zombies attacking the world. Toss the bombs in your grasp close to the zombies, obliterate them and clean the world from zombies. No one but you can save the world. Allow the bombs decisively to go to the zombies. Each level will get increasingly hard.
You need to save the world. Obliterate all outsiders and make the world tranquil. Best of luck!