For my landscape I created a hotel hallway scene where each room opens up to a completely new landscape. Most assets are rendered in Blender, and each new scene choose from two different landscape layouts (flat vs cylindrical), 2 types of trees, 2 types of creatures, 2 types of structures, and 4 or so backgrounds and 4 big structures off in the distance. Basically everything is PNGs, except for the first hundred or so frames which is a mp4. You may have to refresh the page once when initially starting it (I really don’t know why), but after that it should work.
Link to sketch: https://openprocessing.org/sketch/1486536