The number of hackathon events worldwide has nearly quadrupled in the last five years. Despite exponential growth across diverse industries and increasing interest across academic disciplines, our integrated understanding of the phenomena of hackathons is limited. We conduct the first multidisciplinary literature review of publications from 1999 to 2022 to understand the conceptualization of the phenomena over time. We find that hackathon research can be categorized into 4 core areas (purpose, format, processes, and outcomes). Research was first driven by a purpose (innovation, learning, and collaboration), followed by an examination of how formats adjust to purpose to influence what happens (processes) and what is produced (outcomes), and critical reviews of the hackathon phenomena. We contribute a unifying framework with these four core areas to inform future directions of hackathon research and practice, as well as a discussion of the need for longitudinal and multidisciplinary research of hackathons.