This paper presents a proposal and an initial prototype for a Serious Game (SG) aimed at helping second-language learners memorize a list of non-linked vocabulary items under a system of visuospatial bootstrapping (Darling et al., 2017). The usefulness of such a tool was suggested by the efficient outcomes of spatial mnemonics in TEFL providing 21st-century teachers, students, and game designers with new possibilities and it represents a new application of CALL. The game design is based on a modified version of Kalmpourtzis’ AMSTP game design model (2019) and it uses aesthetics, mechanics, story, technology, and pedagogy as its basis, adding the sixth element to its core: user expertise. The resulting AMSTP-UE framework allows in-game analysis from the point of view of a teacher, a learner, or a game designer. The game is a first-person walking simulator using the medium of virtual reality (VR) to provide its players with the feeling of presence in a virtual world. The prototype suggests using visuospatial information, deep learning APIs, and in-game data capture.