In designing for engagement at a public multi-touch installation, we identified supporting multiple users and allowing for gradual discovery as challenges. In this paper, we present Worlds of Information, a multi-touch application featuring 3D Worlds, which provide access to different content. These 3D widgets gradually unfold and allow for temporal navigation of multimedia in parallel, while also providing a 2D plane where media can be shared. We report on a field trial at an exhibition using questionnaires and video ethnography. We studied engagement through questions adapted from Flow, Presence and Intrinsic Motivation questionnaires, which showed that users, overall, had a positive and social experience with the installation. The worlds effectively invited multiple users and provided for parallel interaction. While functionality was discovered gradually through social learning, the study demonstrates the challenges of designing multi-touch applications for walk-up-and-use displays.