The iltur system features a novel method of interaction between expert and novice musicians through a set of musical controllers called Beatbugs. Beatbug players can record live musical input from MIDI and acoustic instruments and respond by transforming the recorded material in real-time, creating motif-and-variation call-and-response routines on the fly. A central computer system analyzes MIDI and audio played by expert players and allows novice Beatbug players to personalize the analyzed material using a variety of transformation algorithms. This paper presents the motivation for developing the iltur system, followed by a brief survey of pervious and related work that guided the definition of the project’s goals. We then present the hardware and software approaches that were taken to address these goals, as well as a couple of compositions that were written for the system. The paper ends with a discussion based on observations of players using the iltur system and a number of sug...