Video games are not just played for fun, they have become a handy instrument for the cognitive, emotional and social development of children. However, several barriers prevent many children with disabilities from playing action-oriented video games, alone or with their peers. In particular, children with severe motor disabilities, who rely on one-switch interaction for accessing electronic devices, nd fast-paced games, that require rapid decision-making and timely responses, completely unplayable. This paper contributes to lowering such barriers by presenting GNomon, a software framework that allows the creation of action-oriented single switch video games. The paper reports the results of two studies that evaluate the playability and rehabilitation-suitability of GNomon-based video games. The playability of GNomon-based games is evaluated by assessing their learnability, eectiveness, errors, satisfaction, memorability and enjoyability, with a group of 8 children with severe motor disabilities. The suitability for pediatric rehabilitation is determined by means of a focus group with a team of speech therapists, physiotherapists, and psychologists from a Local Health Agency in Turin, Italy. The results of the playability study are positive: all children had fun playing GNomon-based video games, and 7 out of 8 were able to interact and play autonomously. The results of the rehabilitation-suitability study also entail that GNomon-based games can be exploited in training hand-eye coordination and maintenance of selective attention over time. The paper nally oers critical hindsight and reections, and shows possible new future game concepts. CCS Concepts: • Human-centered computing → Accessibility design and evaluation methods; Graphical user interfaces; • Applied computing → Computer games;