ACM - affordances
Dominic Elm
Gustavo F. Tondello
Dennis L. Kappen
Marim Ganaba
Melissa Stocco
Lennart E. Nacke
A self-determination theory approach
Classic definitions and new directions
Towards a taxonomy for enterprise gamification
KM QUEST: A collaborative Internet-based simulation game
The kaleidoscope of effective gamification
practices and challenges