As of now this mod adds two mobs neither of which are intended to kill the player. It add serveral new ambeint sounds and effect revolving around caves and being in the dark.
The goal of the mod is to scare the player without needing to repeatively outright kill them and to not overplay its cards. It focused more on ambience and less on adding a mob that just hunts the players.
Mod recommendations: Cave Dust, True Darkness, First Person Model, Crawl, Hardcore Torches (Currently not to version), Void Fog, Dynamic Surrounds (with play scary sounds disabled).
The Claustrophobia Team
