In the dynamic world of livestreaming, capturing audience attention and generating traffic is pivotal for hosts to sustain their income and engagement levels. While various strategies are employed to achieve these goals, the lottery system stands out as a distinctive mechanism, offering the potential to significantly enhance audience participation and platform traffic. Acknowledging the paucity of studies on the nuanced dynamics of gamified lottery, this study introduces a comprehensive investigation into their short-term effects and underlying processes. Employing a quasi-experimental design, the research utilizes an interrupted time series analysis to capitalize on an unexpected suspension and subsequent reintroduction of the lottery function on a leading Chinese live streaming platform. Our findings reveal that the implementation of lottery systems correlates with a short-term increase of 14% in host income and a 10% rise in audience engagement. The findings significantly contribute to the discourse in live streaming and gamified lottery, elucidating the complex interplay between gamification, user behavior, and digital engagement. This study not only deepens the theoretical knowledge but also provides valuable practical guidance for effectively utilizing gamified lotteries, while navigating the inherent challenges and risks in the digital entertainment landscape.