His play Lungs was first produced at the Studio Theatre in Washington DC and has subsequently been performed around the world, receiving its German-language premiere as 'Atmen' at the Schaubühne where it entered the repertory, directed by Katie Mitchell.
[9][10] Every Brilliant Thing was produced by Paines Plough and Pentabus, enjoyed sold-out runs at three consecutive Edinburgh Festivals and continues to tour worldwide.
"[5] Macmillan co-adapted and co-directed with Robert Icke a theatrical version of George Orwell's book Nineteen Eighty-Four, a production that has toured the U.K. and Internationally, had three runs in the West End and played on Broadway in the summer of 2017.
The production was directed by Andrea Ferran as part of the Leverhulme Emerging Directors Bursary and was nominated for four Off West End Awards.
Their collaborations include a play at the Royal Court Theatre titled 2071, which Macmillan later co-authored as a book on climate science with Professor Chris Rapley.
[13] Macmillan's play The Forbidden Zone premiered at the Salzburg Festival before entering the repertoire of the Schaubühne Berlin and transferring to London's Barbican Theatre.
[15] His collaboration with Mitchell led to his meeting Leo Warner, the video designer who directed Macmillan's adaptation of City of Glass in 2017.