I think we should make the basic framework of the game first. Meaning, get it so that we can most multiple islands, also so that all those islands are randomly generated but still have the sense of a custom made map, and get all the animal ideas working.
From the looks of things, we just might be making the animals able to run, sneak, jump, etc. We'll see.
After we get the basic frame work done, then we can turn our attention to little details. This is my own personal opinion.