There are unhinged NPCs that act violently, but they're either shown to be manipulated by a 3rd-party antagonist, or possessed by an aggressive spirit.
The 4th wall is broken very commonly. An entire area consists of the game's developers as regular NPCs with special outfits. A piece of armor is named after the developer's studio name. A questline has the player reviving the protagonist of a separate adventure game from the devs. (with the character encouraging the player to download the game) Another questline also teases the game's sequel "if [the game] gets popular enough." The sidekick character blatantly refers to the game's "Zoom out" mechanic. A guard NPC also mentions the game's Facebook page and encourages the player to leave feedback on the game there.