Mixed reality (MR) games refer to games that integrate physical entities with digitally mediated contents. Currently, it entails relatively high development efforts and technical threshold to incorporate multiple virtual and physical building blocks. Moreover, the absence of a coherent technology stack renders the design and development process even more challenging than conventional digital games. This research proposed an MR game technology stack that affords a wide spectrum of virtual and physical modules with flexibility to adapt to specific application domains and on-cite needs. We adopted a Research-through-Design (RtD) approach. We first surveyed 24 state-of-the-art studies, and results were synergized into three different spectra of technological affordances, respectively activity range, user interface and feedback control. Based on the initial insights, we then went through two iterations and resulted in an MR game technology stack. A user co-design workshop was further conducted, where 15 participants with different game making experiences were invited to try the proposed technology stack, and 4 conceptual game designs were generated after hands-on tutorial and group co-ideation sessions. We also collected participant feedback via user survey and semi-structured interview. The proposed technology stack received an overall positive feedback, particularly the innovative in-game interactions and the motivation for game creation it brought to the users.