Adaptability to the needs of end-users has been identified as a key requirement for technologies designed to support mental health interventions. The PlayWrite system allows end users - mental healthcare professionals - to create and adapt therapeutic 3D computer games, which can then be used to support adolescent interventions. PlayWrite has enabled the creation of games that implement a range of theoretical approaches to mental health interventions and target a broad range of disorders. Here we discuss the initial findings regarding the design, clinical evaluations and adaptation strategies used in PlayWrite. Keywords Mental health, adaptable design, computer gaming ACM Classification Keywords H.5.m [Information Interfaces and Presentation]: Miscellaneous – User-centred design, mental health. General Terms Design, Human Factors