I am pulling the plug, though it's probably obvious to all the game is catatonic. I'd like to thank all who tried, with me, to make it run.
I've learned a few lessons about GM'ing PbP, things I did wrong here, which I hope to use to good effect in the future. Though they may be obvious to others, I'll share.
1) LESSON: Hammer a group together before you start, and do it swiftly. I didn't start with a solid group. Part of that was my fault. Because of the overly clever way I wanted to start (see error two), I actually added to the delay and problems getting a group together.
2) LESSON: Do not get cute with strangers. The startup I had in place put three different runs in the hands of three different individuals, and I expected them to drag everyone else into play. It would have worked with a face-to-face REGULAR group. It probably would have worked for PbPers who had played together for a while. There were too many stall points for the throw-together PbP group.
2a) If I were doing this again, I'd start with one solid, single, small run just to make it a combined group. THEN toss in the actual arc missions that require a bit of finesse.
3) LESSON: Failures to communicate are my fault. More accurately, if the game is stalled it's because everyone's waiting for someone to act. Either they're waiting for me to speak or they're waiting for me to push the person who is supposed to act. Openly prod, quit being considerate and subtle. Better to be loud and wrong than right and, well, have a dead game. Wrong can be fixed.
4) LESSON: Stick to one communications medium. This goes back to being cute, but I started in messages to allow players to have some secrecy and swing. This left a legacy of confusion with players wondering if they should act or not. Next time: if it's PbP, use the OOC for the "private" stuff. Just hammer players if they abuse the secret knowledge others shouldn't know.
Again, thanks to all the players who tried. Hopefully we'll play together in the future -- and actually play instead of, well, see another game die.