I remember my uncle introducing me to this game as a kid many years ago, and to this day, I still have fond memories of playing it for hours on end. It's definitely one of my favorite retro FPSs and one of the most greatest ones created for the PC in the early 2000s.
In the year 2104, an interstellar capable mankind is fighting a hopeless war against an evil entity named Mental and are now on Earths doorstep. Now' it's up to Serious Sam Stone, mankind's strongest warrior, to travel back to Egypt in 1378 BC to discover the secrets of an ancient race called the Sirians to use against Mental in the future and save mankind from extinction.
Serious Sam has a fairly similar formula to Duke Nukem, with its first-person shooting style, extensive armament, alien enemies, and time travel-based formula. And Sam is much like Duke, with his signature sunglasses and spouting corny but badass one liners and pop-culture references, but there's just enough difference for him to be a distinct character.
The game has a bit of a historical aspect since you travel across ancient Egypt, starting at the temple of Hatshepsut and ending at the final showdown at the Pyramid of Giza. The gameplay consists of challenging and hardcore combat against hordes of vicious and relentless enemies that number in the hundreds with an assortment of awesome weapons like rocket launcher, laser gun, and the powerful cannon. Mobility is paramount, and you must move constantly to avoid certain death.
The levels are massive and have beautiful designs and textures for the time, like Egyptian temples and structures with hieroglyphics, mosaics, and carved statues. Exploring them is rewarding and encouraged, as there are many secrets that provide additional weapons, health, ammo, and armor. Other the graphics like explosions, projectiles and blood and gore splashes from slain enemies looked great, and there were tense, awesome sound effects everywhere, from gunfire to enemy sounds. The music ranged from soft, ancient drum beats to intense and heart-pumping action with guitar riffs and deep metal vocalizations during boss fights.
I loved the wide and crazy variety of enemies, with the Bio-Mechanoids, Kleer Skeletons, Arachnoids, and (in)famous Beheaded Kamikazes with their constant screams and inescapable suicide attack. But the final boss, Ugh-Zan III the warlock giant, stood out the most and gave the game a huge and spectacular ending.
This game has aged very well over the years and its fun factor holds up as well, so try out the HD Remake on Steam if you'd like.