This question is a follow-up to How has knowledge of the Ur-Hamlet evolved over the centuries? in which we learned about how it first came to be postulated that Shakespeare's Hamlet was based on an earlier story of the same name by a different writer. Another question naturally arising out of this is, given the assumption that there was an Ur-Hamlet, whose text is now lost, what can be deduced or at least solidly guessed about its content? Even though the text itself is lost, references to it remain in other pieces of literature, and perhaps there's more evidence to be found in other Hamlet-like stories from around the same time. I don't need certain proof, but clear evidence based on serious studies would be good, not just pure guesswork.