Updated December 23, 2015 to cover refactoring -- the inner story has been fully outlined now, which changes the estimates. As of this writing no new work has been done since my last update in 2014, though I intend to change that soon.
Note: Estimated time to complete is not elapsed time to complete, it's worked time. In other words, if I say it will take 2 hours, it means 2 hours of total writing time, which may take place over the course of a year. It is not an estimate of how quickly you'll get the story, but of how much effort lies ahead of me before I finish it.