I sort of hate to do this, but...
For awhile before I came back here to the asylum (yes, I was here once upon a time, perhaps under a different name), I was an avid Marathoner, and checked the marathon story page frequently. Matt Soel, Bungie's public relations dude, mentioned three cool new things. One was Halo, another was the Mac Action Sack, and a third was supposed to be a special surprise for the Marathoners. Although I can't be sure if these are essentialy the same three things nathan mentioned, it seems likely to me that Total Codex will probably be the las Myth thing for awhile.
But I could be wrong. =)
In the event that I am, I'd like Bungie to release the COMPLETE sets of tools this time, including the anomalous Vegas, and whatever they use to import and animate sprites (although Amber IS a masterpiece...)
Joyeuse
