This thesis challenges the common social construction of game development, which perceives the activity only within its commercial, corporate realm. As an exemplar of the many thriving amateur development communities, the self-identified “homebrew” Nintendo Game Boy Advance (GBA) development community is analyzed in-depth. This unique community is brought to the attention of scholars as an important intersection of game studies and amateur media studies, challenging the focus of game studies on commercial production. The GBA homebrew community is studied from the personal motivational level to the social dynamics of the group. The analysis considers the blend of technological and cultural motivations brought to bear on the production and the content of the amateur games, and how amateur development facilitates skill acquisition outside of canonical academic structure, and opens access to professional mobility. The case study advances both historical and contemporary comparisons to other independent media communities. The thesis also examines discussions in the community around peer-judged competitions as a form of vernacular theory. The content of homebrew GBA games released into the community are further analyzed, with the construction of useful categories spanning genre, fan games, remakes, remixes, and tech demos. Nostalgia and parody in relation to game history are especially considered, as are demonstrations of technical skill (“tech demos”) as a uniquely amateur practice. The legal context of amateur GBA development is also examined. Nintendo maintains the GBA as a closed, proprietary system, and thus for homebrew developers access to information and legitimacy is blocked. Comparisons are advanced to historical examples of intellectual property enforcement in the emergence of corporate media in the 20th century. Amateur practice is found to be tangential to corporate interests, ignored both by the disinterest of corporations, and in blanket policies targeting piracy. Historical cases that legitimate reverse engineering of software are discussed for context. Thesis concludes that one cannot cleanly construct categories of amateur and professional as separate practices, and remarks upon the constant renewal and shifts in amateur development communities as new game platforms are released in the commercial market.