How is this different from an ordinary breadth-first search (with pruning)?
Immediate edit: So on a lark I looked up "tilde ath" and found someone actually implemented some of it [0]. It's more focused on bifurcation than threading, and I think it might be improved by something like OP's `quantum`. At least we could simulate the plot a bit.
Regardless, I was sad about that as well. You just can't appreciate the MRDV properly without it. [1] Or without the ensuing War & Peace-sized volumes of comic/chatlog either, I guess.
[1] http://vignette4.wikia.nocookie.net/mspaintadventures/images...
[2] Only Duff's Device comes to mind here, but I think we're looking at something more pathological with the MRDV