Defining gameful experience as a psychological state caused by gameplay: Replacing the term ‘Gamefulness’ with three distinct constructs

•A multilevel process theory of gameful experience is developed and presented.•The term gamefulness is replaced with three more precisely defined constructs.•Gameful design, gameful systems, and gameful experiences are carefully defined.•This theory links these constructs causally whereas previously they were confounded.•This theory thus serves as a unifying foundation for future work on gamification.