Dyslexia is a widespread specific learning disorder, which can have a particularly negative influence on the learning success of children. Early detection of dyslexia is the foundation for early intervention, which is the key to reduce the adverse effects of dyslexia, e.g., bad school grades. In this paper, we present the prototype of a puzzle app, which we explicitly designed with the human-centred design (HCD) process for dyslexia screening in pre-reader using new indicators related to motor skills to ensure users needs for the data collection to apply machine learning prediction. The app records the telemetry of the gaming sequence in order to derive future statements about the prevalence of dyslexia based on the telemetry data. The high-fidelity prototype was evaluated with a five-user test usability study with five German-speaking child-parent pairs. The results show how young children and parents are interacting with new games, and how new applications (web and mobile technologies) which are used for online experiments, could be developed. The usability of the prototype is suitable for the target group with only minor limitations.