Board Thread:Game Discussion/@comment-29636239-20180329121715/@comment-29746749-20180329151421

I know they are awarded sequentially. Engineer, then Agent, then Manager, for example.

You do not have to use them all to get another one. For example, I used to use the engineer and save the Agent for a few days. Eventually I got another Engineer without ever using the Agent.

Other than that, I have no idea what the algorithm is.