I was looking at my dev diary from summer to this point and there is surely an interesting trend for increasing amount of development. It's also showing in the new LOC chart (starting from summer):
LOC has increased "only" 2000 lines, but it's quality code! Most of the source code is already in place and only involves some adjusting. Not to mention removed code, there has been some of it also.
This December was actually the best month in development point of view. I was able to complete or almost complete several major classes and the work is now more and more focused on narrow set of classes which have the most difficult problems to solve (AI, item routines, advanced level generation, etc.).