In previous research and development, the project team created a prototype of a web-delivered game to engage middle and high school students in in foreign languages, including Spanish and Mandarin Chinese. In the game, students practice languages by finding a solution to a mystery by engaging with characters and navigate changes in the plot to an ongoing story. In this project, the team will develop a prototype of an artificial intelligence-based app that personalizes the game by adjusting content to the level of each student at the start and making content more challenging as students' progress. In the Phase I pilot study, with 100 middle school students enrolled in Spanish, the researchers will examine whether the prototype functions as intended, if middle school students able to participate in the game successfully, if the app is challenging but playable for students at different proficiency levels, and if students increase in from a pre-test to post-test on a researcher developed measure of receptive and expressive vocabulary in Spanish.