Creature Isle is an expansion pack, but it doesnt play in the same fashion as the original Black and White. For example, the battling of rival Gods is gone.
The story goes a little like this. A group of creatures have lost their Gods and have formed a brothership. In order for your creature to join the ship, he must first prove himself through a series of initiation ceremonies. The trials can be fun, and include tasks such as bowling, hide and seek with an invisible wolf, or racing.
Completing these trials is the path to gaining acceptance from Mercutio, the giant crocodile founder, and guardian of Eve, the only female creature on the isle. You can guess where this is going. Offspring are inevitable, and soon you can be the proud owner of a baby creature, ready for your parental care. Dont worry, there are crèche facilities available for when it gets a little too troublesome for you. Train your young tyke well and one day he will grow up and prove himself as a worthy leader of a creature brotherhood.