It is crazy how common and how widely-developed craziness is, in role-playing. As much as world-building, as much as combat options, as much as magic systems, this is a definite feature of the hobby with its own schools and aims. It is clearly a primary path toward characterization, character development, player agency (through its managed lack in many cases), and emergent plot.
It might be the winner so far among Monday Labs for many game titles are packed in there, and I'll bet that viewing and comments will yield at least as many more. I know I forgot to mention Personality Traits in Pendragon as a great example of "acting out" design, and Silence Keeps Me a Victim by Clyde Rhoer and The Dreaming Crucible (author name by permission only), as what might be called the Processing zone of this topic. In chatting beforehand, Jared Sorensen suggested we need a mosaic of all the RPG covers that feature distorted screaming faces ... and I wore out before completing it, it was endless.
The question, and I think a genuinely fruitful one, is how mechanics which constrain or dictate character behavior, and in many cases remove immediate player agency, play such a powerful role in validating characters and events, and why we as players often seek them eagerly. Students of catharsis, tread carefully.
As a minor point, I would love to play in a game featuring only Malkavians, but my stumbling block is that I don't understand why it would have anything to do with vampires.
I mentioned my game in design, Estimated Prophet, so here's the direct PDF link. le mon mouri certainly qualifies for similar reasons.