This subdirectory contains puzzle implementations which are
half-written, fundamentally flawed, or in other ways unready to be
shipped as part of the polished Puzzles collection.

Those puzzles which have .R files can be built as part of the
Puzzles collection by symlinking their source files into the parent
directory and re-running mkfiles.pl. Anything without a .R file
isn't even finished enough to do that, and you should read the
source file itself to find out the status.