Advertising has become one of the major sources of game apps revenues and interstitial ads, in particular, are the most used monetization method among the types of in-game mobile ad formats. Interstitial ads overlaid on top of a mobile game app have more obvious advertising intent and a higher degree of forced exposure and perceived intrusiveness. This study examined how the degree of congruity (high vs. moderate vs. low) between the promoted products in interstitial ads and the mobile game app environment affects consumers' responses. The moderating effects of media-context factors (i.e., excited-or calm-happiness game types and game immersion) were further assessed. The results of two experiments revealed that game-product congruity lead to better consumers' responses toward ads and advertised products. The positive effects of game-product congruity were more salient when consumers played calm-happiness games and were less immersed in the game. Theoretical implications on integrating perspectives across disciplines such as schema theory, happiness, and immersion within the media-context framework, as well as practical suggestions are discussed. K E Y W O R D S game-product congruity, happiness, immersion, in-app advertising, mobile games Psychol. Mark. 2019;36:229-246.wileyonlinelibrary.com/journal/mar