Vivarium [Horror]

A central Guilt value rises when the player kills mobs or mines most blocks, and the game's progression follows that value. As it climbs, the environment shifts: water fog slowly turns red, the music pitch drops, hostile mobs spawn more often, passive mobs flee, and neutral mobs attack on sight. Sound effects such as heartbeats and crying appear at intervals, especially underground, and the sun can change into a crying eye. Rain turns to blood after a certain point.

The mod also adds custom hostile entities and scripted events. A broken log can bleed a pool of blood, a cave may teleport the player somewhere nearby to disorient them, and a heat wave can cook armor under the sun. Blood is a liquid found deep in the earth, and a massive World Tree with a World Heart lies underneath. Dream sequences lead toward a knife that completes the mod's progression. Content Warning and Blood Self-harm are listed as themes on the mod's page.

Vivarium is released under the MIT License and is open source, with public source code and an issue tracker. It targets Forge only, with builds for 1.20.1, and both the server and every player need it. An in-game config menu lets the server owner adjust the pace of events.