Mental’s horde is trying to take over the whole world — the entire humanity is in great danger. The world is virtually enslaved — there remains just one place not under the horde’s rule. Its protection is provided by the Earth Defense Force commanded by Sam Stone. The alien invaders do not willing to give up and begin attacking with reinforcements, but Serious Sam, along with his well-armed soldiers, will do everything possible to stop the enemy.
They will have to fight with numerous Mental’s minions, including Beheaded Kamikazes, Beheaded Rocketeers, Kleer Skeletons, Scrapjacks, Sirian Werebulls, Khnums, Processed Antropolyps, Emetic Antropolyps, and Octanian Zealots. Sam’s team is equipped with the most modern and powerful weapons that the guys successfully use in the fight.