the game are twin automatic Uzis replacing the tommygun from the earlier games of the series. Plot The game's story picks up shortly after the end of Serious Sam: The Second Encounter, with the hero of the series, Sam "Serious" Stone, continuing his goal to defeat his nemesis, Mental. The game begins with Serious Sam being summoned before the Sirian Great Council, where the Council provides him with guidance on how to accomplish his goal to defeat Mental. The Council reveals to Sam that he must collect all five pieces of an ancient Sirian medallion, each held by various races on five different planets, and states that once Sam has the entire medallion, Mental will be vulnerable. All the planets (except Kleer) are populated by friendly, bobble-headed humanoids, but the problem is that all the planets are under Mental's control. The Council then instructs Sam to visit all five planets in order to recreate the medallion, only then will Sam become "The One". Confused at the moment and with nothing better to do, Sam accepts the mission. With the medallion finally complete, Sam is now ready to begin the final assault against the greatest enemy of humanity... Mental, who is located on Sirius, once the planet of the great Sirians that visited Earth many times, now the domain of Mental himself. But in order to gain access to Sirius, Sam is asked to storm Kronor, a moon orbiting Sirius that has a massive cannon which could be used to remove Sirius' protection shield, which was a last line of defense for the Sirians against Mental. And so, Sam's mission continues. In the endgame, Sam enters Mental Institution after disabling it and into Mental's throne room. Sam finally encounters Mental in person while the lights are off. Mental tries to reveal to Sam that he is his father, but Sam interrupts by shooting him, thus silencing Mental forever. After that, the Sirian Great Council, even the inhabitants from the planets, celebrate their long-awaited victory against Mental. When the lights come back on however, it is revealed that Mental wasn't there at all and it was instead just a speaker attached to Mental's throne, implying that he actually tricked Sam in order to escape in his starship into deep space (in the Xbox version, the game doesn't show this scene). The credits roll after that, where a dialog of three unknown people