This document discusses the ARLearn toolkit for creating mobile and virtual reality applications for serious games. ARLearn allows for the creation of augmented reality, augmented virtuality, and mobile apps using tools like notifications, rich media, and a data model. It also describes some case studies using ARLearn, including language learning games for children, cultural science fieldtrips, and a hostage simulation for training critical situations. The document promotes ARLearn as an open source toolkit for building immersive educational experiences across different delivery channels.