Some comments on the XP lifecycle phases defined by Beck:
Like many projects, XP can start with exploration. Some story cards (features) may be written, with rough estimates.
In the Release Planning Game, the customers and developers complete the story cards and rough estimates, and then decide what to do for the next release.
For the next iteration, in the Iteration Planning Game, customers pick stories to implement. They choose stories and thus steer the project based on current status, and their latest priorities for the release. Developers then break the stories into many short, estimated tasks. Finally, a review of the total estimated task-level effort may lead to readjustment of the chosen stories, as XP does not allow overworking the developers with more than they can do based on "family-friendly" work days, such as an eight-hour day. Overtime is seriously discouraged in XP; it is viewed as a sign of a dysfunctional project, increasingly unhappy people, and dropping productivity and quality.
Developers implement the stories within the agreed timeboxed period, continually collaborating with customers (in the common project room) on tests and requirement details.
If not finished for release, return to step 3 for the next iteration.