Sculk Echo

Sculk Echo builds a progression around echolocation and sculk. A pulse, bound to the V key, emits a sonar wave that paints nearby creatures and blocks as point-clouds. Mobs that move leave sound-trails, and the sonar reveals the Warden's sonic boom once the player copies it with the R key. Players gain these abilities over time, and the Deep Dark and Ancient Cities are the places where most of the progression happens.

The infection is the central threat. Sculk spreads as a disease that walks through the environment and turns zombies, skeletons and pigs into infected mobs with veined teal skin. An infected creature can strike a victim with claws or an arrow, and a hit has a 15% chance per strike to raise the victim again as infected. The infection moves through five stages, and infected mobs never despawn, so they roam the Deep Dark for good. Players stay on the edge of the risk by standing too long among them.

Sculk Echo is a Client and server mod, so the server and every player need it. It is published for NeoForge 1.21.1 only, under the MIT License, and is not open source. Ancient Cities and the Deep Dark come from vanilla, and the mod requires them to be present in the world for its progression to start.