Netherworld Covenant places the player in the abyss, where the mortal world and the underworld intertwine after a catastrophe. As a survivor, the character wields the Lantern of the Void, an artifact that connects the two dimensions. This item lights up with azure flames, allowing the player to traverse procedurally generated labyrinths and destroy cursed barriers. The goal is to confront fallen heroes and demonic overlords to uncover the truth woven from blood and soul. In this world, the lantern serves as a conduit for summoning the fallen.