The study looks at the effectiveness of in-game advertising, focusing specifically on the impact of medium context. Using an experimental design, the study investigates the relationship that exists between the effectiveness of in-game ad placements and a player's psychological experiences in reaction to the content of the game. It is argued that the numerous emotions and experiences that occur during game play (e.g. enjoyment, competence, tension) might have an impact on how players process the game environment, including in-game ads. In order to test this, a between-subjects online experiment was conducted in which participants played a casual PC game that contained several in-game advertisements. We manipulated the difficulty of the game, leading to differences in several player experiences between experimental conditions. Results indicate that increasing game difficulty affects the processing and evaluation of the brands featured in in-game ad placements both directly and, more importantly, indirectly through the variation of player experiences.