Cristian Galliano created a 3D level in Unity by first making a playable character and then building up the terrain using tools to create a mountainous island with grassland, beach, and forest areas, adding textures and smoothing heights. He continued developing the level by adding a second island with a lake and pier, then removing planned elements like a volcano and instead adding rock formations and detail like trees and rocks. The level included two islands connected by a pier and had varied biomes, but he noted areas that could use more detail.