I was horrified when sheep started throwing themselves off of the cliff! How did they even get up there in the first place!?
Amazing work, really tight art style, and a very effective design!
Improvement wise, perhaps you could ramp difficulty on a less harsh curve? Introduce cliff edges as a gameplay obstacle along herding pathways. Maybe you could then add wolves that chase after sheep, or giant birds that swoop down and pick them up? Not sure what counter play to this would be... perhaps just whopping them on the head with the herding stick?