Obacon — At least 1 character in this game is an obacon. Obacon is the opposite of lolicon: attraction to older women. It could be grandmothers-like, mothers-like, or even older sisters-like. The important point is that the obacon go after only older and/or more mature women.
Object Heads — One or more characters in this VN have inanimate objects for heads. If this is due to the anthropomorphization of an inanimate object, include that tag alongside this one. An Object Head is a visual motif often used in surreal art. It is generally used to symbolize a connection between humanity and an inanimate symbol.
Observer Protagonist — The protagonist in this story acts only as an observer to the action or story. They take no meaningful actions other than to relate the story to the reader or their actions are of little consequence to the plot or characters. Not to be confused with No Protagonist or Third Person Narrative. The protagonist in this story is a real person that simply doesn't get involved. They may be part of a.
Obsession — One of the characters have an obsession that plays an important part in this story. It may be a revenge the protagonist is obsessing about or it may be a heroine obsessing about uncovering a certain truth. Don't use this tag on the games where a heroine is insisting on eating something... but on games when it is a factor of psychological drama.
Octopus — This game has one or multiple octopuses taking an important role in the story. Or it has octopuses all around in multiple scenes with several lines of dialogue related to them.
Odyssey — For a large part of the story, the protagonist (and his associates) travel from one place to another - whether they are trying to find a way home, or have some loftier ideal.