Cello Fortress is a unique combination of a game and a live music performance. A cellist defends a fortress by improvising on his cello. Melodies control the guns, dissonant notes activate the flamethrowers. Players from the audience use game controllers to steer their tanks and attack the fortress. The cellist plays live music, while at the same time controlling the game to be a fun challenge for the players. Cello Fortress is an innovative experiment that blends concert and game.