Good news: I've completed parts 1-4 so far. Rough drafts, obviously, but the story's in place generally speaking. Bad news: There are now 6 parts, not including the 'endgame'. Plus, I still haven't done any work on the real art yet. I expect to have most of the rough draft finished in a week or two unless I burn out again. I'm not sure that's as much of a problem with Ren'Py, though, since I can play through the game piece by piece as I make it and the whole process is satisfying in immediate and obvious ways. To be continued.