A while back, on a very boring day, I developed a system for counting through events. The idea was to create a new chapter goal, Kill X Enemies, X being determined by the person creating the chapter, of course.
Just to note, this counting system is actually quite flexible and can be applied to many other situations. Just trigger the countdown event some other way and let the counting begin. This works because the countdown is triggered by the killing of enemies, but it can really be applied to anything you desire. I don’t have anything explicitly in mind, but I’m sure some creative soul could come up with some other hypothetical uses for countdowns.