Some nine years ago, I published this post on Andrew Ferguson’s NYRSF piece on unpublished R. A. Lafferty works. These included:
I also knew about the unpublished “In a Green Tree” novels:
(A project fifth volume, In the Akrokeraunian Mountains 1978-1990, was evidently started but never completed.)
I was also aware of the third and fourth volumes in the Coscuin Chronicles series:
However, this wiki (evidently created by Ferguson) includes still more novels I haven’t heard about before:
Not listed there, and only listed on a couple of dubious webpages, so I have my doubts as to whether it actually exists, is The Giant Ratchet of Sumatra (with Sharon Scott). There is a reference to a first chapter manuscript in the University of Tulsa archives, but I see no sign that it had ever been completed.
Excluding the dubious and unfinished, by my count that’s fourteen unpublished Lafferty novels…