In 2007, I supervised an internship for the Adaptive Music Systems Research group under Jan IJzermans. The group  researched adaptive sound design and composition for games and developed the Adeptive toolkit, which helps composing in nonlinear settings.
To make things clear: we’re not talking about composing a song from the beginning to the end (linear music); the composer makes a large amount of musical ‘cells’ and the system selects new cells based on the rules of the composer (nonlinear music). Such an approach can be highly suitable for games, that mostly have a nonlinear character, as the music is able to correspond with the narrative or the presupposed experience of the player. And at least, we’re preventing the repetitive background track that drives players crazy.