This paper describes the development and evaluation of a mobile assisted language learning tool that teaches some aspects of the Maori language within a virtual game world. The game uses a simulated world, which reflects aspects of Maori art and culture, to structure Maori language learning experiences. It was developed using the Corona SDK and can be deployed onto multiple platforms. Android tablet devices were used for our evaluations with learners. The approach to language learning theory embodied in the game is based on a well-established Maori language learning technique known as 'Te Ataarangi.' This is modelled on 'The Silent Way' method which uses Cuisenaire Rods. However, rather than rods, the game uses the relationships between virtual characters and artefacts in the game. A design science research methodology was used, with prototypes being developed and tested with teachers, students and academics as design partners. This involved testing early prototypes with educators, then subsequently whole classes of students. In between testing, the software was redeveloped based on the observations and feedback collected. Classroom observations during the iterative development cycle showed the tool was both engaging and effective for vocabulary learning. Knowledge was generated about how a wide range of game mechanics can be used in a game world to structure mobile, Maori language learning experiences. Quantitative evaluation showed that students were able to learn vocabulary over a short time using the tool.