...Has anyone actually made an anatomical horror project?
A system which operates outside of your control, constant and steadfast- more complex than any machine, defined by an endless loop of processes that no one has gotten to the bottom of, work which is absolute and must continue, but undescribed, unknown- forceful.
Yames' style of horror (Discover my Body, Water Womb World) utilizes push factors, things which force you, or your character directly into the depths- curiosity which damns you, like a child discovering something wrong (and, like a nightmare, are punished in a horribly overblown way.)
One game of theirs, "Discover My Body" uses the lens of anatomy as both a push factor and the main concept- something which you cannot run from, something you must bear, something that is given to you in hearty detail that you must absorb... It's main focus is the transformation, and the anatomy thereof rather than the existing systems of the human body.
[Extreme flashing light warning if you choose to play "Covetus", t let it be known the creator wishes it not to be.]
An old newgrounds game titled "Covetous" follows an exaggerated case of two medical conditions ("Fetus in Fetu" / Parasitic Twin), the plot of which being that you control the "Brother" of a victim, subsisting entirely on the biological systems of the host (Though not anatomically accurate)... The gameplay is simple, but utilizes a sort of x-ray perspective as the game space.
Though not horror, the series "Trauma Center" utilizes strange (but fantastical) diseases and illnesses as a central plot point: E.G,
-A "Fish" that swims within an organ and causes large amounts of lacerations within a split second
-A parasite which creates a web to "sap energy" from a victim's heartbeat
-Tumors which, when cut can randomly explode in a cloud of harmful gas.
...
On a totally unrelated note, I vaguely remember a snippet of a horror movie on Cable TV- perhaps distorted through my bouts of childhood sleep paralysis, and the general state of "Concious Unconciousness" between the 2-3 minutes of "Wake" and "Dream", right as your eyes start to slip.
It was an "Osmosis Jones" sort of closeup (Camera pan to chest, cut to a menagerie of "Veins" inside of a body.)
...
I'm not sure if I could make one, I'm far too "esoteric" for horror, and unlike the fetishists' "Gleeful" interpretation of the macabre, I don't have the heart nor skill to describe things directly.