The Grand Tour is a feature of Descenders, introduced on October 28, 2021.
The Grand Tour is a series of optional missions that can be completed to acquire rare Developer gear sets. These missions are split into various groups, with each group being called a "tour". Tours gradually increase in difficulty, and they have to be completed in order before the next tour can be worked on.
5 missions have to be completed in a set to unlock the next set. Each completed mission will award a random Item. The first two tours will award a random common item each, the next two will award a random uncommon item each, and so on until the last two tours award a random extraordinary item each.
Completing each tour awards two pieces of the Developer Gear set mentioned in the name of the tour.