It turns out that Yukaghir has a rather unusual split-intransitive core case system: Yukaghir combines pragmatic roles with syntactic roles in this cool little system:
topic focus O O-topic O-focus S S-topic S-focus A A-topic A-focus
So, unlike most languages - which get by with two cases for this (and I mean two cases even for isolating languages - many languages, including English, do have syntactical features that distinguish subjects from objects in a very case-like manner) - Yukaghir has four here. Further, the O-Topic (green) is marked as S/A-topic if the A-topic outranks the O-topic in a person hierarchy (speaker > non-speaker).
A-focus is the least marked form, and apparently for most nominals mostly identical to S/A-topic - third person pronouns being the exception where they're always distinct.
This interacts in weird ways with the verbal system, to which I will return in a follow-up post. For now, grasping this should be a good start.
Elena Maslova, Tundra Yukaghir, Languages of the World/Materials 372, 2003, Lincom Europa.