In this paper, we discuss the need for new approaches to research regarding coding to support students in developing practices in computational thinking, such as abstraction and decomposition, in multidisciplinary contexts. We explore students' activities with a tool integrating constructionist textual programming activity with game-based learning and specifically game modding. In this context, we designed a programmable 'design-to-play' game developed with the computational environment MaLT2. MaLT2 offers the affordances of textual programming, dynamic manipulation, and 3D navigation for the design of 3D animated models aiming to give children access to, otherwise, complex, computational and mathematical ideas. To develop an understanding of children's learning activity regarding computational practices, we organised an empirical study with middle-school students, who played a game called 'Code-the-Mime'. It is a charades-based game in which the players manipulate, programme, and modify a digital human model to describe a word to their teammates. The preliminary findings indicate that the affordances of MaLT2 in conjunction with the game context enabled students to express and develop key computational practices, including decomposition, pattern recognition, analysis and abstraction, in a meaningful and multidisciplinary context. Practitioner notes What is already known about this topic Computational Thinking is considered a key 21(st)-century skill in preparing the young to become digital citizens. It involves concepts and practices that can be used to solve problems computationally across multiple fields. However, there is still limited knowledge of how students develop computational practices, such as abstraction, pattern recognition, decomposition, and how they may express and apply them in diverse contexts. Students' engagement with computational practices is unlikely to be supported either by closed, simplified coding tasks or higher-level advanced programming exercises. There is a need to clarify the manifestation of these practices and how they can be realised and expressed and used by learners in meaningful and transdisciplinary contexts. What this paper adds It suggests the design of constructionist computational games that integrate design and programming into the gameplay, aiming to engage students with computational practices in a multidisciplinary, authentic context. It provides an example of a 'design-to-play' charades-like game, developed in a 3D modelling programming environment, that embeds real-life representations into computational design, to enable 'syntonic learning' of computational practices. Furthermore, it analyses student learning activity to elaborate on arguments and issues related to this approach. Implications for practice and/or policy There is added value in disconnecting computational thinking from positivist diagnostic approaches related to respective concepts and studying it in ways more related to realistic problem-solving situations and multidisciplinary contexts. The study contributes to the scientific clarification of computational practices concerning how they are being realised and expressed by the students in different contexts through an original example of educational practice. The discussed approach and tools can contribute to the design and development of innovative digital media, embedding affordances for concepts and practices while maintaining relevance and interest for their users.