I present a project in which we had no limitations to how the game would work or play. We ran into our fair share of problems but we manage to put something together. It could still use plenty of work but please leave helpful comments and tips.
http://dl.dropbox.com/u/56647679/ClockWork.html
If you are new and this is your first experiment with unity, then this is a great start. But all you do is shoot gears at people made of blocks.
It needs an objective.
You should add some colliders the machines on the first floor, also add a delay to the shooting : )