Lennart Nacke. From playability to a hierarchical game usability model. In Bill Kapralos, Andrew Hogue, Ricardo Mahoney, Jay Raynovitch, editors, Proceedings of the 2009 Conference on Future Play on @ GDC Canada, Vancouver, BC, Canada, May 12 - 13, 2009. pages 11-12, ACM, 2009. [doi]
Abstract is missing.