Engineers or Scientists?
There are two types of staff available in the game - Engineers and Scientists, whereas the whole mechanic revolving around them differs tremendously compared to the first XCOM game. First things first, the amount of staff you have at your disposal will be a lot smaller now - no more dozens upon dozens of engineers on board of your ship. You will have a few of them at most, but don't worry - it's a normal thing. Secondly, their participation in your operations is greater now.
Engineers are used to excavate rooms, increase the speed at which facilities are constructed, and finally increase the effectiveness of those said facilities. From the two types of staff the engineers are more important (especially in the first few months of the game), because without them the development of your base will come to a halt. The more engineers you are able to attract to your base, the better.
The case with the Scientists looks quite different. They are used to fill two facilities (Laboratory and Shadow Chamber), which means that they will be completely useless during the first few weeks of the game and they will simply have nothing to do. That is why you shouldn't really exceed more than one scientist before you even think about constructing the Shadow Chamber. That facility is able to use every single one of them, and the more you have when you decide to perform a research there the better, as those take a lot of time to complete.
In general, it's worth to stick to those three rules when it comes to acquiring new engineers and / or scientists:
- During the first few months of the game you should focus solely on acquiring as many engineers as possible - every single one will increase the speed of your base development and will increase the inflow of resources (as excavating gives them).
- If you are planning to build a Laboratory, you should acquire at least one scientist - you will be able to place him / her into the facility, which will decrease the time needed to perform researches.
- When you get to the later part of the game and the necessity to construct the Shadow Chamber starts appearing on the horizon, try to accumulate as many scientists as possible - each one of them will decrease the research time in that facility.
How to acquire staff
Engineers and Scientists are acquired from the same sources, which are:
- Black Market - each time you get a supply drop from the Council (once a moth), the Black Marked will be stocked with new items. There can even be a scientist or an engineer to purchase for some Intel.
- Resistance HQ - each time you collect the supply drop from the Council, you will be prompted to go into the Resistance Headquarters to do some shopping. Along numerous soldiers and boosts to your HQ, there sometimes be an engineer, or a scientist to purchase - this time by using Supplies.
- Completing missions - probably the main source of staff members. They come as a reward from a number of missions - mainly from the Guerilla Ops, or as a rescued VIP. You should always check what each mission gives in return and should pick the staff members - resources, items and soldiers can be acquired from a number of different sources.