Hard to say overall, because it depends on how much content we plan to add for the final release. But in terms of the pre-alpha stage, I would say we're about 50% done.
Minor Update: Finally got the custom shaders working again, which supports both opaque and transparent colors. Building controls have also been added, and are mostly finished:
Also tested compiling an external build / application of the game, i.e. for the eventual demo release.