BACKGROUND AND AIMS: There has been much concern regarding potential harmful effects of video game-play in the past 40 years, but limited progress in understanding its causal role. This paper discusses the basic requirements for identifying causal effects of video game-play and argues that most research to date has focused upon ambiguous causal questions.

METHODS: Video games and mental health are discussed from the perspective of causal inference with compound exposures; that is, exposures with multiple relevant variants that affect outcomes in different ways.

RESULTS: Not only does exposure to video games encompass multiple different factors, but also not playing video games is equally ambiguous. Estimating causal effects of a compound exposure introduces the additional challenge of exposure-version confounding.

CONCLUSIONS: Without a comparison of well-defined interventions, research investigating the effects of video game-play will be difficult to translate into actionable health interventions. Interventions that target games should be compared with other interventions aimed at improving the same outcomes.