Ludum Dare 50 happened recently (a 72-hour long game jam). My friends and I created a silly infinite runner called Bath Time. I was responsible for all the 3D elements in our project. All of our assets and code were created in the 72-hour time window from scratch. To quickly make variation in our environment, I created an HDA that allowed for creating multiple 100x100 terrain prefabs in engine with scattered objects (rocks, grass, cactus) on them. The HDA was brought into Unity, converted to polygons, and then customized in engine to create a terrain of your liking. We then saved the crafted terrains as prefabs. These prefabs were then randomly selected to be placed in front of the player.