As Rambo, you will try to kill all of the zombies on the map. The monster will always find a way to beat you, stay alive, and try to save the world.
The hero figure is immortal, even with his own weapon, so you can bomb wherever you want. The green monsters will be hidden in any location in the warehouse beneath the tunnel. Destroy them all; leave no objects behind since they will threaten the city. This duel tests your skill to aim properly; they have obstructions, so they must use the grenade's reflex lines to explode. All collisions will have the same inertia as in real life, making it possible to forecast and deliver accurate shots. Make excellent use of the instruments available to assist you in approaching the demons. Only once you have cleared the creatures will you be able to take part in the following battle.
Have fun and good luck!