Really cool idea and game! I love games that have an ecosystem to them. An idea that I have for this is starting at the top animal and working down and trying to become the dominant species. This would lead to harder difficulties and starts the player off being a bear! For becoming the dominant species, that would mean knowing where other animals' habitat is, what they eat, and what their predators are. I think that could lead to a unique strategy game once those places and nuances for each animal are set leading to a complex ecosystem. This would however change the whole game idea so your choice. Really fun game especially considering it was made in a week!