The study aimed to adapt Nick Yee’s Motivations of Play in MMORPGs Inventory into Russian. The sample included 538 participants (72.5% male) aged 12–40 years. We used Gaming Motivation Scale (GAMS) and the flow experience in group role-playing games questionnaire to assess the external validity of the adapted inventory scales. The final version of the questionnaire reproduced the original factor structure, but contained 24 items out of 39. The indicators of the final model fit (CFI = 0.95; RMSEA = 0.042) demonstrated good agreement between the model and the empirical data. Cronbach`s alphas varied between 0.619–0.906, suggesting moderate to good reliability. The correlations between Yee`s Inventory scales, GAMS scales, and the flow experience questionnaire confirmed its construct validity. Intrinsic motivation, integrated and introjected regulation (GAMS) mostly correlated with the factors of the Immersion scale. Identified and external regulation mainly correlated with social and achievement motivation factors. There were no significant correlations for GAMS amotivation scale. All scales of Yee`s Inventory correlated with the flow experience; multiple correlations were also found between achievement and social motivation factors and focus on communication and thoughtfulness-spontaneity factors of the flow experience questionnaire. Male and female gamers scored differently in Yee’s Inventory: men had a significantly higher interest in mechanics (achievement scale). Women had higher escapism and customization motivations (immersion scale). We consider the adapted version of Yee’s Inventory a reliable and valid tool to evaluate online gaming motivation.