Several are confirmed collaborations, including Pericles and Henry VIII (and 1 Henry VI is almost certainly).
The exclusion of 2NK is a bit arbitrary but you draw the line somewhere. I also excluded it from my quest to do every play.
In the end I did it as a Zoom production, which kinda half counts, as is appropriate. It was actually a good deal better than I expected. I found some very good writing, and the plot was easier to clean up than, say, Two Gents or All's Well.
> Also, around 20% of plays credited to Shakespeare were collaborations of some degree, though the collaboration details have been long lost.
Isn't it accepted that The Two Noble Kinsmen was a collaboration?
EDIT:
> [On Hamlet] You’d be hard-pressed to find something that beats the faithful, star-studded 1996 major film adaption.
Personally, I liked the (less faithful) 1948 film.