Changes worldgen to go down to -512, and adds difficult and unique challenges every 50 meters below zero. Highly configurable.
Below 0: Slowly lose sanity in the dark, and gain sanity in the light. Insanity can cause issues like blindness, hallucinations, and blackouts.
Below -50: Slightly increased hunger.
Below -100: You cannot sleep. Going multiple days without sleeping will increase sanity drain and incur mining fatigue.
Below -150: You are weaker, and enemies are stronger.
Below -200: Wear a Gas Mask or hold a Toxin Amulet to avoid dying in toxic gas.
Below -250: Regeneration is disabled, and plants cannot grow
Below -300: Monsters can spawn from broken deepslate or netherrack.
Below -350: Brace your armor with copper (or netherite) to survive the crushing pressure.
Below -400: Blazes can spawn anywhere, regardless of light level, and even near the player. (Nether mobs also spawn at this level).
Below -450: Catch fire instantly unless wearing netherite armor (or under the effect of fire resistance).
Below -500: Implode instantly from the pressure unless wearing armor braced with netherite.
Balancing changes:
-Netherite upgrade template is craftable
-Armor trims are far more common (5 times) in Ancient Cities
Every penalty can be changed to a different height, or disabled completely via config.

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