Internet Gaming Disorder [IGD] has recently received nomenclatural recognition from official medical bodies as a potential mental health disorder, despite evident variability and inconsistencies in its core conceptualization and psychometric assessment. In the present review, the authors argue how the adoption of inconsistent criteria and psychometric tools to assess IGD negatively influenced the field. Additionally, this review provides an overview of how the field evolved in terms of its historical developments, present definitions and frameworks, developments in the neuroscientific research, psychometric assessment, and emerging trends in the assessment of gaming addiction. After a careful review of the literature, it was concluded that (i) research on gaming addiction dates back to the 1970 and since then important changes in the field occurred, especially in terms of (ii) definition and conceptualization of the phenomenon, which resulted in a (iii) multiplicity of strategies in the assessment of IGD via inconsistent criteria or psychometric tools. Lastly, it is presented (iv) alternative emerging methods for assessing IGD via sound psychometric tools based on updated and officially recognized conceptualization of the phenomenon of IGD.