Underground Survival Lighting
Arkatron

If you like underground light in survival, use this mod, it can help that.

Exile Rails
programmerjake

Adding underground rails and trains to Exile

Hades Endgame
VeproGames

Adds various goodies to Hades Revisited, focused on Late/Endgame

Nyancat's heaven (reworked)
Hybrid Dog

Adds a nyanland in the sky

NodeCore SeaLife
Winter94

Adds Biodiversity to NodeCore Seas & Rivers

Natural slopes for Hades Revisited
karamel

Add natural slopes for Hades Revisited

NodeCore Nature: Revised
Warr1024

Updated, fixed, enhanced edition of Winter94's NodeCore Nature

Archaeology
SkyBuilder1717

Adds an looting and API in archaeologing

Sun Flowers
Hybrid Dog

This mod generates flowers which close their heads at night.

Startest
Robot10&Scheletor

This mod adds several space stuff to the game.

golden lava
GigaByte

add golden lava

Boulders
Neuromancer

Adds pushable boulders which spawn in dirt & stone. They tumble when they wind up on top of each other and cause damage when they fall on you.

NodeCore Fossil
Winter94

Discover fossils, oil, natural gas, amber, and more!

NodeCore Pottery
Winter94

Adds clay and ceramic items and nodes to NodeCore

Sticks Stones
MikeRedwood

Makes Sticks from leaves and scatters small stones

NodeCore Vuga
Winter94

Generates Vuga Underground.

Alien Tools
chaosomnium

Alien Tools Mod for Minetest - adds Alien Tool, Shield, biome, etc

NodeCore Crystals
Winter94

Adds various crystal types to Nodecore

Beautiful Boulders
regulus

Procedurally Generated Rocks with (pretty) Accurate Collision Boxes

Advanced Biome Decoration Modpack
EmptyStar

A collection of advanced biome decorations

morebiomes
mzs.112000

A simple mod adding a few biomes to Minetest Game

Fly-B-Gone!
Hugues Ross

Hides butterflies/fireflies

Dirt Tunneler
Neuromancer

Makes dirt deeper and you can tunnel through it just by walking through it. Press spacebar/shift to tunnel upward/downward with auto placed ladders.

NodeCore Fungi
Winter94

Adds various fungi to NodeCore, in all their mycelial glory.

Spawn redo
cathaya7d4

Drop-in replacement for default/spawn for more third-party biomes

Purple ore
X-DE

Adds new purple ore to floating islands and caves from height 200 to 31000.

Trucraft
mt-mods

An alternative crafting system done entirely in the world.

NodeCore Coal
Winter94

Adds 3 ores of coal to NodeCore.

Tac Nayn
GreenXenith

Adds Nyan Cat's evil twin, Tac Nayn (and a gray-scale rainbow).

More Coral
Nathan.S

Adds coral in more colors.

NodeCore Stalactites & Stalagmites
Winter94

Generates Stalactites and Stalagmites in caverns underground.

Unstable Caves
M BLOC

Some stones may cave in if punched, making underground expeditions more risky.

treasures
ademant

Treasure nodes with useful items

Fragments
Amaz

A mapgen with a goal, with things needed to advance to the next level.

World Borders
argyle

Add impenetrable barriers to the sides and bottom of the world.

Obdy
Sires

Adds some pretty OP tools :)

Euthamia
Avicennia_g

Grassy Goldenrod plant for Nodecore

NodeCore CatRealm
Warr1024

Adds a cat-themed dimension with unique ores and over-powered tools

Fix floating sands!
1F616EMO

Avoid hanging sands and gravels

Easter Eggs / Ostereier
Ineva

Adds various coloured eggs for Easter!