Its not the micro controlled system that gets the marks.. Its the work you put into it (theory etc..) for all the good of it, sequential flashing lights would do it if your write up is sufficient.
Use your imagination. If you're going to be a successful engineer you're going to have to solve other people's problems. That will require imagination as well as technical knowledge.
Rather than us doing all the work for you, I suggest that as part of the project you learn what a control loop for a switching regulator is. I'm sure Google can find numerous references.
What level of school is this for? If the above is too complex for you then you should find a simpler project.