What is the author's style in Amadeus by Peter Shaffer?

The play is structured like a deathbed confession, similar to Monticello's in Edgar Allan Poe's short story "The Cask of Amontillado." The play opens after the main events have occurred and with one of the main characters, Antonio Salieri, speaking to the audience as an old man. Salieri frequently addresses the audience directly, sometimes in an aside, during the course of the play to gain support and understanding.