A self-sustaining civilization of robots. Humans are gone, but generations and generations of robots evolve and, eventually, incorporating organic compounds, they become cyborgs.
However, the robots were doomed by their limited intelligence and their fervor to produce additional robots. The robots eventually depleted all available resources, thus making the planet uninhabitable for themselves.
Until they learned to explore the cosmos and do this on planet after planet leading to the Grey Goo[1]. Or the flipside, in that they create a Big Bang to reverse it like the multivac did in Asimov's The Last Question when they finally have sufficient information to process it.
If you would assume technology to another biology- then a error is a mutation, thus robots would divide into predators and hunted animals, resulting in a new wildlife.
