Lambdarune is a take on Deltarune by Zet. It's a Deltarune AU that includes original Chapters 3 to 7, with some subtle things in Chapters 1 and 2 being recontextualized. Lambdarune is Zet's main project and has been shown through animations, music, and mostly community posts… until now.

The game is structured into Chapters 3-7, with each chapter divided into 2-4 Installments.