The playing tiles offer a new way of making music, and can also serve as entertainment while you wait for the train and want to be slightly creative. The tiles can learn to play the way you want them to. Depending on how the user moves on the surface, the tiles can learn how to play certain harmonies. Every tile is a note, and when a tile is stepped on, a couple of the tiles make a chord. If the user doesn’t like the harmony of the chord, he or she tries to move in another way, until the tiles play the way the user wants them to. In this way the system gets only "positive feedback". The tiles currently playing are lightening. The rythm of the song is depending on how fast the user is moving on the surface.