Watching Macbeth last night spurred on a few ideas, as it always does. Mostly visual ones in this case, as the production is heavily stylised and riffs on the Russian Revolution and Stalin's reign of terror, but it's as good an alternate setting for the events of Macbeth as any.
So, what else could we borrow from the Shakespeare tragedies?
Usurpers: He was fascinated by usurpers, rightful heirs exiled and all that. A good hook for any plot with people in power and people expecting to inherit or claim it afterwards. (A bit inconvenient for the classic power-politics game, Vampire, of course.)
Crimes so dreadful that nature rebels: Signs and portents, storms, horses going mad and all that business. Caused by regicide in Macbeth but these days largely reserved for supernatural activity that draws a supernatural response.
One murder is never enough: As also seen in the work of the Coen Brothers, the killer's best chance to get away with murder is to keep killing people who know too much or ask the wrong questions, and this can spark off a few other motives for killing as well, and eventually the rest is silence.
Prophecy: Being able to write what he will without the players going off in different directions makes it easy to weave in prophecies and have them pay off. A GM generally has to have at least a couple of possible meanings for a prophecy. (And even then, Macduff obviously spent a few Drama Points to "reveal" he was born by C-section. J.R.R. Tolkien so disapproved of this unguessable un-foreshadowed twist that he restaged the final battle with Eowyn, after having the wood come to Saruman's castle much more literally too.)
Ghosts, or possibly not: Most of the time, only the haunted character sees the ghosts... Hamlet's father appeared to other people to begin with, but later only to him, so maybe some of his appearances were just in Hamlet's mind. How to do that with a PC? Talk with the affected character's player away from the others?
The sympathetic monster: There's nothing like a bit of extra time on stage to let us sympathise with the villain. If all we see is the results of his actions, and then meet him at the final battle, we aren't going to see his point of view. Of course, this needs players who don't roll initiative at the first sign of an enemy, like Macbeth and Macduff only have that one scene together.
The unsympathetic sympathetic monster: So, having set things up so that the players spend time in-character with the villain, you have to make sure they still know he deserves stabbing/poisoning/beheading when the time comes. So he's a regicide, he steals his late brother's wife, he spends all his time telling the audience how clever he is...