The chapter investigates how the identity and agency of a language teacher are constructed through the use of a suite of videogames originally designed for vocabulary practice, called ELLE: the EndLess LEarner. A unique aspect is that the teacher had the rare opportunity to contribute to the game development and to be one of its first testers in its multiple versions. Using reflections, autobiographical interviews, and journal entries, the chapter illuminates how this teacher’s perceptions and pedagogical values evolved in relation to the game. Her agency as an instructor, an expert in her discipline, and an emergent gamer were strongly intertwined. The findings also show that she employed the game as a technological tool to achieve socially situated goals.