Along with sending Specialists to complete tasks, there is one other major requirement for completing the bunker. During the second construction phase, players will need to use Engineer Depots to convert Specialists to Engineers. Once a Specialist is trained, players can establish Engineer Outposts. There are four types of Engineer Outposts that players will need to establish: Medicine, Ecosystem, Life Support, and Defense. Each one will increase the percent of the chosen category's research for the Doomsday Bunker.