This work presents a VR based serious game for children with ADHD and aims at providing an evaluation of the acceptability and the usability of an application developed to create a meaningful and motivating environment for the child, capable of supporting the development of the various attentional components. Due to the Covid-19 pandemic the evaluation was performed online offering also the opportunity to test the feasibility of a validation remotely performed. The expert involved in the study expressed a positive judgment on the application, considering it understandable and easy to use. Moreover, they confirmed that the actions performed by the operator, during the remote sessions, were clear and made it possible to understand the tasks required within by the serious game, thus enabling to provide evidence on such kind of remote validation.