What are the considerations one has to take into account when writing a play, that are imposed by the format of a play, a.k.a by the fact that it is played on stage?

For example, in Shakespeare's time, all "corpses" had to be carried off stage, because there was no curtain and no lights that could be turned off, so the corpses couldn't just get up and go away. (Particularly noticeable at the end of tragedies, when there are many corpses to be carried away. That's why we have Fortinbras in *Hamlet*, for example.) Today, of course, no such consideration exists.

Another example: classical ballets are structured in such a way that the principals can catch their breath after a demanding pas de deux. This comes into play not just during staging, but already at the stage of writing the score.

An obvious theatre consideration is "people can't fly" (unless the production has a lot of money), same for other special effects. **What are other considerations that must be taken into account when writing a play that living people would have to perform on stage?**

To clarify, **I am not interesting in *staging*** - that could be re-imagined depending on who's producing the play. **I am interested in *that which has to be written from the start*, by the playwright**. Shakespeare had to write Fortinbras in from the start, so that someone would be there to remove the corpses in the end.