My first idea was to make a juggling siteswap visualizer, which the professor thought was uninteresting. So I stopped at making bouncing blocks. I wondered what it would look like if I just made a ton of bouncing rectangles:
The next idea, which I eventually presented in class, was "ElevatorCorp", an idealized simulation of an office building where all the workers do is ride elevators all day. I used three.js to talk to WebGL.