Ripper (1996) with Christopher Walken and Paul Giamatti came on 6 CDs
Also https://en.wikipedia.org/wiki/A_Fork_in_the_Tale - not a good game, but an impressive number of CDs at 5
Also https://en.wikipedia.org/wiki/A_Fork_in_the_Tale - not a good game, but an impressive number of CDs at 5