Seeded 2D Perlin noise is used to generate a 48x48x24 voxel terrain with different blocks based on height.
Every coordinate on the floor of the terrain (the x-z plane) has its x and z values passed through a Perlin noise function, which then generates a semi-random decimal between 0 and 1.
That decimal is then scaled by the total depth allowed by the terrain, which determines the height at that point in the x-z plane in voxels.
It's like Minecraft, but worse. 🎉