The working title for the dark fantasy rule set that I have been working on for a while was The Final Castle, after the tentpole dungeon of its default setting. However, for some time now I have been thinking that it would be better to give the base rules a different name and perhaps work on the setting and module part separately if for no other reason than to expedite finishing the rules (which are very close to being done).
I still like the name Hexagram (based on a previous, incomplete rules experiment). Parts of it influenced work on The Final Castle anyways. Also, as a potential base to build from, Hexagram has a more pleasing ring than The Final Castle.
So, The Final Castle is a setting/mega-module. Hexagram is a rule set built around the Hazard System and a flexible, classless character progression system. Hopefully the change in naming is not too confusing. I am not sure exactly what to do about the blog tags but whatever.