In this article, the authors begin this inquiry by describing their research with a class of middle school writers who played "Quandary," a free online educational game designed to teach argumentation, as part of a unit on writing arguments for environmental action. Regarding the subject area of English language arts (ELA), research has tended to focus on the integration of digital, online games in reading instruction. Less attention has been paid to how digital, online games might be used to promote students' writing. Argumentative writing receives a special place in the Common Core State Standards across disciplines and grade levels. Available online for free at www.quandarygame.org/, "Quandary" asks players to assume the role of space colony captain on faraway planet Braxos. "Quandary" allowed students to test potential solutions to the "water war" dilemma, with facts that might serve as supporting evidence, on various characters in the game to gather arguments for and against their eventual recommendation to the Colonial Council back on Earth. Digital, online games, like "Quandary," can provide not only material for students to write about but also invitations for students to write in the game to solve problems -- problems that may have real-world relevance.