The Planets[]
M'Digbo (populated by Simbas) - M'Digbo is a tropical paradise that is spoiled by Mental's forces. Here, Sam recovers the first part of the medallion after he defeats his first major enemy, Kwongo.
The Simbas
Magnor (populated by Zixies) - The world of giant trees and objects makes Sam feel like a toy soldier... Here, Sam conquers the second part of the medallion after he defeats Zumzum.
The Zixies
ChiFang (populated by Chi Che) - This planet looks like a Chinese land and features many oriental stereotypes. The third part of medallion is received after Prince Chan is killed.
The ChiChe
Kleer (populated by Kleers) - Kleer is a home planet of the skeletons from Kleer, the enemies heavily featured in the previous Serious Sam installments. Kleer is fiery planet filled with lava. Its inhabitants are all undead Kleerians, and thus enemies. The fourth medallion part is taken from Kleerofski, the ruler of Kleer.
Sam gets serious on the Kleer homeworld
Ellenier (populated by Elvians) - Ellenier is fairy-tale based planet which features beautiful landscapes, towns and castles. The final part of the medallion is located here. Sam acquires it by defeating Cecil the dragon.
Elvians defending their homeland
The fairytale inhabitants of Ellenier
Kronor - Frozen moon where many of Mental's base and forces are located. Here, Sam has not only to conquer the enemy's base and remove the protection field of Sirius, but also to help various people from the planets he visited, who are being held here as prisoners. Serious Sam wins the battle for Kronor after he crushes Hugo, a massive robot dispatched by Mental.
Sam tackles Hugo on Kronor
Sirius (populated by Sirians, but now is Mental's main headquarters) - Sirius is the home planet of once great civilization. The traces of Sirians were seen many times by Sam in Earth's past. However, the time of Sirius' glory is over, as Mental took over the planet. Sirius is high-tech planet full of skyscrapers, energy fields and other stereotypical science fiction scenery. Here, Sam's final battle against Mental forces take place. However, when Sam makes his way to Mental's heavily protected HQ, the Mental Institution, he has to protect himself from the building itself, which is revealed to be quite powerful adversary.
Rigil Kentaurus- Rigil Kentaurus is a system filled with wastelands and is home to the Marsh-Hoppers.
Reeb- Reeb is a planet that is home to the Reeban Electro-fish.
Aludran System-The Aludran system is a planet in the constellation of Canis Major and home to the Aludran Reptiliods.
Beelmez IV-Beelmez IV is a mysterious planet once home to the Zorg warrior race until teleported by Mental to fight in his army.