It means whatever you want it to mean. The point is to get you talking about a project you care about. About the specifics rather than generalities. Your comme

It means whatever you want it to mean. The point is to get you talking about a project you care about. About the specifics rather than generalities. Your comment sounds like a perfectly fine answer to me. I personally would ask you which project was the most interesting to work on? Or which were you most disappointed by when it didn't ship? And why. At least, that's what I'm looking for when I ask it.