The concept for the title originated from the idea of a Whale Fall. A Whale Fall refers to the ecosystem created when a whale carcass falls to the deepest parts of the ocean where no sunlight exists. An ecosystem develops around the carcass that lasts for decades before disappearing completely.
Much like a Whale Fall the ecosystem and creatures of ProtoProfundum exist off the carcasses of human beings. Whether the world is an isolated subterranean ecosystem or some form of afterlife it was designed to be highly hostile towards the player and increasingly disturbing.
The creatures inhabiting the environment are entirely self composed of human remains. Not being able to generate flesh themselves the acidic rivers are used to digest and mold the fallen carcasses into specially designed constructs.
The level design was built around light stealth and avoidance tactics against larger and threatening creatures. The limitations of these creatures is important to the design of the encounters. Scavengers by design the creatures will not take notice to anything a level above them and retain a limited cone of vision. Levels were designed to teach these behaviors and build upon them in future engagements.
In order to achieve a structured challenge for the player a synchronized path architecture was engineered. Synchronizing the movement along several paths and creatures allows encounters to be tightly designed in a way that creates openings for the player that are closed further into the challenge.
Faster paced running sections were designed to accompany the more stressful stealth sections. The players is asked to move through a dark space which harbors clouds of smaller creatures in the shadows. Driven away by light these creatures will attack the player when in darkness. The player runs through the shadows utilizing a light projectile driven by a cooldown. These projectiles are used to drive away the creatures and activate bubbles that act as a shield against the creatures.