Manchán has written & produced 3 bilingual plays

and 3 theatrical installations exploring Irish language & culture.

Broken Croí/Heart Briste was nominated for 2 Irish Times Theatre Awards, the Fishamble New Writing Award and the Bewleys Café Theatre Award. It won the Stewart Parker Irish Language Award in 2010.

He received a commission from the Project Art Centre to write Bás Tongue, which was directed by Willie White at Dublin Fringe Festival 2011. It was rewritten and reproduced by Team Theatre as Focal Point, with Mikel Murfi as director in 2013.

Manchán was commissioned to write a bilingual play for the Abbey Theatre in 2011, An Love Mícheart which won the Taidhbhearc's Walter Mackin Award in 2014.

In 2015 he debuted the Gaeilge Tamagotchi, performance installation at Project Arts Centre as part of Dublin Fringe Festival, 2015. It has since toured widely, including to the Kennedy Center in Washington DC.

In 2018 he debuted Arán & Im as part of the Abbey Theatre's tour of Jimmy's Hall. It has since toured to every country in Ireland, and will now head to North America and England in 2022

His third theatrical installation is Sea Tamagotchi for Galway2020,  culminates in Spring2021, with over 200 evocative coastal words projected onto the walls of Dublin city, and also 20 videos of individual words, with also a handmade book by RedFoxPress and a short film.