Started reading an LP of Drakengard.
The only three words that can describe it are What, The, and Fuck.
I remember that game.
It isn't the most disturbing game I've ever played, but it does rank pretty high on the list.
At the point I'm reading at (It's the old DarkID one in the LP archive, I have SA archive access and am reading the whole thread), the description given by one commentator "So far, it appears you've been taking control of a mute and murderous sociopath, accompanied by a blind pedophilic monk, an old ink-head and a cannibalistic manic, running around a snow filled desert, slaughtering Pig-cops and midgets and listening to a giant dragon telling you about your sister's apetite for your cock." This seems quite accurate, and the thread assures that this is just the tip of the iceberg.
You know a game that tops this?
Huh, pretty sure the mute wasn't pedophilic, but instead had a massive martyr complex resulting from the death of his younger siblings. He stabbed himself in the throat because a pixie taunted him to do it, then made a pact with it to survive shortly after. In the sequel he's stated as spending his life in the aftermath of Drakengard being nice to kids as far as I remember.
The elderly priest sacrificed his hair as part of his pact and is one of the most evil pricks in the game when you get right down to what the seals are. F*ck you baldy, f*ck you.
By cannibalistic maniac I assume you mean the elf? I don't recall her being cannibalistic, but she did have an obsession with murdering children. Something to do with her going mad after her kids were killed by the 'Evil Empire' and her womb being sacrificed as part of her pact with a pair of elemental spirits.
Caim is almost a sociopath but not quite from what I recall, he cares about his sister and his friend. He also softens up a lot as the game progresses and he stops hating the dragon so much. Though yeah, his sister wants to bang him. Depending on how things go as you play the game one scene can either have her killed by the BEG or kill herself rather than confess her incestuous desires.
The endings are all pretty messed up. Very messed up really... Incredibly messed up in fact. I'll avoid spoiling it though. Though I will say that the BBEG is a 6 year old girl.
Honestly though the game never really made me go WTF that much, I found The Darkness, in which you watch the main character's girlfriend get her brains blown out in front of you while you're restrained by the darkness from before creation and get a drill used to turn your skull into a colander, F.E.A.R and a few others more WTF inducing and more creepy. Hell, Bioshock creeped me out more, what with implanting sea slugs into brainwashed little girls to make an immortality drug that gave you horrible cancers and let you shoot bees from your veins.
Oh, and F.E.A.R. 2, which ends with you getting raped by a psychic ghost woman. Who may or may not have been a teenager, I forget. That made me go WTF.
Drakengard 2 was, oddly, less weird than the original, despite the main character being dragon jesus.
I think I'm just resistant to WTF though, I can't really think of much that's actually made me go WTF properly. Might be a result of spending my childhood reading a book series that can be summed up with 'the main character's best friend/caretaker gets eaten alive in front of him in the first book, and it gets darker from there.'