Like previous titles in the series,
Serious Sam 3: BFE involves fighting against many hordes of enemies in wide-open environments. However,
Serious Sam 3 has more closed environments than its predecessors, particularly in the early levels. There are also a larger number of enemies that can attack the player from a distance. There are 13 weapons in total, five of which have a manual reload. The signature close-combat weapons from the first game, the knife and chainsaw, have been replaced with a sledgehammer with three modes of attack. In the style of old-fashioned first-person shooters, there is no regenerating health, instead, there are health and armor power-ups scattered throughout the levels that the player must pick up. Additionally, the levels are full of secret areas, where health, armor, ammo, and in some cases, weapons from later levels can be found, following the tradition of the previous games. Some weapons such as the Lasergun and the Sniper Rifle and their respective ammunition pickups are secret-only and otherwise are not found in the levels normally. There are no puzzles, however, the player must find keys, pull levers, and find environmental anomalies to progress. Classic enemies such as the Beheaded Kamikaze, Beheaded Rocketeer and Kleer Skeleton return in the game. New ones include the Khnum and Scrapjack (resembling the Hell Knight and Mancubus from
Doom, respectively), as well as the cloned soldiers reminiscent of the Strogg from the
Quake series. The Kamikaze has returned to his original design, rather than the
Serious Sam 2 design. The Gnaar's design has radically changed from the original game. It is now much larger, differently shaped, and walks on all fours, unlike its bipedal counterpart in the original.
Serious Sam 3 features some new gameplay mechanics such as sprinting and iron sights. Unlike most other FPS games that have sprinting, the player is able to sprint as much as they want, but they cannot attack while sprinting. The pistol and assault rifle have the ability to aim down sights, which increases accuracy but only slightly. The player moves slower while aiming down the sights, making it impractical at close range. The player can perform hand kills or kick enemies to conserve ammo, depending on the weapon selected. For example, a Gnaar's eyeball can be ripped out or an Antaresian Spider's shell can be broken. == Plot ==