Product placement in social games has become a growing trend in recent years. Based on mere exposure effect and dual-process theory, this paper develops a theoretical model to examine the effects of interactions and product information on the initial purchase intention of social gamers in the context of product placement in social games. The moderating effects of product familiarity are also examined. Results show that interaction with product and sociality affect the positive emotion of social gamers in relation to the virtual product in a social game, and the positive emotion affects the social gamers’ product interest in the actual product. In addition, positive emotion directly affects the initial purchase intention of social gamers in a heuristic approach; and perceived usefulness and perceived entertainment gained from the provided product information affect the initial purchase intention of social gamers through product interest in a systematic approach. Finally, the results show that product familiarity is an important moderator.