A few folks on ModDB (and elsewhere) have been asking about the mod's progress. It's been long enough now that I'd like to give a quick update.
First of all, the mod is still under active development. It fell totally behind schedule in summer 2016 owing to unforeseen issues (both development and non-development), but a new revised release plan has been devised.
To date, my release estimates have been fairly inaccurate. The estimates didn't take in account the possibility of me throwing away vast chunks of the project and starting again. In 2014, when the project was fairly new, I had completed the basic design for all the levels I intended to be in the mod. At the time, it seemed that there wasn't much to do beyond adding polish and tidying a few things up...
Looking at the levels I have now, only one of the levels from the 2014 era actually remains. It's a hard decision to chuck a level out and begin afresh but it has led (I believe) to a stronger single-player campaign... and, admittedly, a longer development period.
I'm not going to commit to dates publicly until I am sure (or as sure as one can be) that the dates I provide aren't going to shift. However, saying that... I do intend to have the first internal beta ready for testing come April 30th. The beta will be very close to the end product, minus a few textures and models. On that date, I hope to be able to give a final release date.
Sit tight. This has been the longest and most difficult project I've ever worked on, but the end is in sight.