The goal of the Guided Tour was to lower the barriers to entry into the product and improve the retention of new users, by teaching them how to complete high-value actions.
The rocket motif arose from the theme of learning and exploration, since new users would be in 'unfamiliar territory'. The progression of graphics helps reinforce that users are successfully completing each step in the tour.
The interaction model was finalized and optimized to work across various locales and screen resolutions. This was reflected in the redlines and accessibility spec that were handed off to Engineering.