Not replicating existing animals

I want the world and the evolution to be completely random, and not based on things we see in our own evolution. No giraffes, no hippos, cocker spaniels and no pterodactylus. I'm not replicating existing animals.
I'm actually not replicating the concept of animal either. The simulation simply features organisms with basic traits, and then the evolution itself takes care of the rest. If an organism evolves into something with a long neck that moves about on four long legs and consumes parts of another tall stationary organism, then I'm here for it.
An evolution in the simulation may very well produce something completely different, just as viable as a giraffe is in our evolution. That's what's so much fun about this. It makes no assumptions about what should happen. Things just happen because of logical behavior in a deterministic, but highly unpredictable, environment.
You may have theories about whether our universe is deterministic or not, and about the immense philosophical implications of both options.
So do I.