As 모바일 카드 게임 becomes globally widespread, many worry that an expansion of 모바일 카드 게임 aggravates educational inequality and ultimately intergenerational mobility. We address the issues by estimating the average and distributional effects of 모바일 카드 게임 on academic outcomes of Korean middle school students. Applying a semiparametric model recovering distributions in difference-in-differences models, we discover that the presence of 모바일 카드 게임 shifts the upper half of the outcome distribution rightward, but it exerts statistically insignificant effects on the lower half of the distribution. Our result suggests that the expansion of 모바일 카드 게임 in an education system is expected to aggravate educational inequality more than an empirical method reporting modest average effects suggests.