A cult is most commonly defined as a religious group that preaches unorthodox believes, granted a lesser state of credibility than "real" religions and are often derided for their extreme practices and viewpoints. Ostensibly, the difference between a cult and religion is popularity. So there, that's a nice inflammatory lead into the main article.
It's about cults in videogames. Enjoy!
The Mythic Dawn (Oblivion)
Considering the fact the Daedra are demons, several of whom take active pleasure from the misery and suffering of mortals, pretty much any of the Daedric cults found in Oblivion are certifiably insane. However, the followers of Oblivion's principal baddie, Mehrunes Dagon, take home the loony prize.
The ultimate goal of the Mythic Dawn is to allow an army of slavering, malformed, vicious Daedra to invade Tamriel, and it's fairly safe to assume the region's inhabitants will all be put to uniform slaughter. Members of the cult believe that they will be reborn in Camoran's Paradise, which of course is actually a Hellish pit of misery where cultists are tortured in the name of larks and japes.
For wanting to trade the lives of an entire world for a bit of power, and for being incredibly stupid at the same time, the Mythic Dawn definitely deserves a placement.
The Saturnine (BioShock)
To be considered crazy by an army of drug-crazed lunatics, one must be incredibly, impressively demented. That alone is condemnation enough for The Saturnine, a nature-worshipping cult first introduced in BioShock. The other citizens of Rapture simultaneously fear and revile this "aging bunch of fratboys" - and considering that Splicers are, by and large, all insane and hideous, it takes a real special quality to be seen as the worst of that bad lot.
The Saturnine are named after the Roman God of agriculture, Saturn. They like to wear masks made of wood and little twig antlers, and apparently sacrifice pumpkins to the gods they serve, which appear to be appropriated from other aspects of Roman mythology. They also have a bad habit of mixing up Plasmids and human blood to create a substance they call "Ambrosia."
Yeah ... them's gone all zany.
The Covenant (Halo)
Like all good religions, The Covenant masks bigotry and intolerance under the guise of prophecy and divine law. Basically a bunch of racists, this theocratic military force from the Halo universe comprises a number of alien species united under the belief that humans are an affront to the gods and must be eradicated.
Slightly more sinister than holding a bake sale to save the church roof.
The Covenant's doctrine stems from an incorrect interpretation of something said by total strangers thousands of years ago, and yet from this bad translation comes an entire army of zealots who either believe everything they're told with blind faith, or have been conscripted, indoctrinated and essentially forced to swallow what they're being force-fed.
Sounds kind of familiar, actually.