Monetization is fundamental to “free-to-play” mobile games, typically in the form of advertising placed within gameplay. Monetization within digital games is linked to deceptive design, and other ethically dubious practices such as loot-boxes. However, it is unclear what impact monetization has on the overall player experience. This research measured the experience and player performance in an experimental “Pong”-style game in three conditions: no advertising, static-interstitial advertising, and video-advertising. A between-subjects study was carried out with 95 participants aged 9-11 years playing the game in one of the three conditions, then completing the FunQ questionnaire. Results showed that while the static-interstitial advertising condition had a negative impact on player experience and player performance the video-advertising condition did not. Findings were ‘reported back’ to a group of the original child participants, feedback gathered during this session showed that children understood the findings and were able to contribute both additional insights and ideas for future research.