More Coral
Nathan.S

Adds coral in more colors.

Sun Flowers
Hybrid Dog

This mod generates flowers which close their heads at night.

World Borders
argyle

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

golden lava
GigaByte

add golden lava

Tac Nayn
GreenXenith

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

morebiomes
mzs.112000

A simple mod adding a few biomes to Minetest Game

Unstable Caves
M BLOC

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

Spawn redo
cathaya7d4

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

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.

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.

Obdy
Sires

Adds some pretty OP tools :)

Underground Survival Lighting
Arkatron

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

Sticks Stones
MikeRedwood

Makes Sticks from leaves and scatters small stones

treasures
ademant

Treasure nodes with useful items

Mud
Blocky Player

Adds stylish mud blocks and even blocks you can walk through. Setup traps, secret rooms and much more!

Silver
Jackknife

adds silver ore and tools