NodeCore
Warr1024

Minetest's top original voxel game about emergent mechanics and exploration

Visual Bots
Nigel

Visually programmable turtle bots

Mesecons
Jeija

Adds digital circuitry, including wires, buttons, lights, and even programmable controllers.

PaleoTest
ElCeejo

Adds Prehistoric Fauna and Flora to Minetest Game