According to the plot, in the middle of the 21st century, humanity began to discover artifacts and ruins left by the ancient Syrians, a long-forgotten extraterrestrial race from the planet Sirius. At this time, Mental, an extraterrestrial Overlord, awakens from human inactivity and sends his hostile alien armies to attack Earth.
Sam “Serious” Stone, the captain of Earth’s Defense Force, sets out with a small Squad of soldiers to Cairo, Egypt, which has been occupied by Mental’s alien army for some time. Their mission is reconnaissance with Bravo team.
The main theme of the game involves battling small and massive hordes of enemies, often in large open areas. The player can also carry an unlimited amount of weapons. There are a total of 13 types of weapons, with 5 of them featuring manual reload. The melee weapons from the first game, the Combat Knife and P-LAH Chainsaw, have been REPLACED with a sledgehammer with three attack modes (vertical strike, 180-degree swing, and full 360-degree swing).
Serious Sam 3: BFE offers several game modes, both online and offline. In the offline mode, the player can play the single-player campaign and survival mode.