Abstract
Intelligent environments and smart applications require creating engaging interactions with their users, which on one side requires sensing and understanding human behavior, and on the other side carefully engineered application interfaces to keep these interactions sustained and useful over longer periods. Playful interactions and serious games incorporate elements of play for this purpose. As a fundamental human activity, play engages people at every age. This thematic issue explores how novel technologies can fuel fun and entertainment in ambient intelligence applications, and the societal implications and possibilities thereof.