Initially when learning my way around the Unity3d engine I wanted to make a zombie shooter. A very popular genre and it seemed like a good starting point. In doing so I got around to using most of the common components for working with the 3d engine like Mecanim, animation system, physics colliders/triggers, lighting, particle system etc.
However, after working on this project for a while, I decided to join teams with a small group of enthusiastic indie developers Big Red Planet. Which meant that the work on the zombie shooter was discontinued.