Children with attention deficit hyperactivity disorder (ADHD) experience behavioural and learning problems at home and at school, as well as a lack of self-control in their lives. We can take advantage of the evolution of new technologies to develop applications with the aim of enhancing and stimulating the learning process of children with ADHD. In addition, these applications may help teachers and therapists to track the progress of the children. In this paper, we present a novel software system with new interaction mechanisms with the aim of improving memory and attention in children with ADHD. The system is based on a set of collaborative games developed in a novel multi-device environment applying the distributed user interface paradigm together with tangible user interfaces (TUIs). The interaction with the system is very intuitive and simple as children interact directly with known physical objects used as TUIs instead of using the mouse and the keyboard. In this way, children can play while moving around the room and interact with the games that are projected on the wall.