Attention Deficit and Hyperactivity Disorder (ADHD) is associated with symptoms of inattention, hyperactivity, and impulsivity and affects a significant part of the population. Current treatment approaches entail high costs and are commonly based on stimulant medication, which may lead to undesirable side-effects. FocusLocus is an EU H2020 Innovation Action project that proposes a highly disruptive and innovative gamified monitoring and intervention programme for assisting children to manage and overcome ADHD symptoms. FocusLocus implements game mechanics that rely on cognitive training methods for mental and motor skill acquisition and behavioural change. The proposed programme is delivered through a multifaceted and adaptive gaming experience that permeates the child’s daily life and activities, spanning across virtual and physical space and comprising two modes: (a) a mobile tablet game for home use by individual users and (b) a multisensory mixed reality game for supervised sessions at specialised facilities (e.g., clinics). FocusLocus is designed to be highly personalised and adaptive to each child’s individual condition, symptoms, age, and character. By introducing advanced remote monitoring and management features, FocusLocus actively involves all stakeholders associated with children with ADHD (parents, clinicians, and special needs educators). FocusLocus employs an unobtrusive and multimodal sensing, assessment and monitoring methodology relying on (a) mobile device embedded sensors, (b) Electroencephalography (EEG) neurofeedback mechanisms, (c) Augmented Reality (AR) user tracking, (d) RFID-based object tracking for tangible user interaction, (e) in-game cognitive skill performance measurements, (f) cloud performance analytics, and (g) web-based secure access for remote profile monitoring and management.