This tech tree, compiled and created by MenhirMike, shows which reseearch as well as building facilities need to be have completed before getting a certain piece of tech. The latest update fixes a lot of the incorrect research requirements and also adds the different requirements needed across all difficulties.
The color codes are as listed:
- Black: Missions, actions or item drops in the game
- Red: Research
- Purple: Proving Grounds projects
- Blue: Items
- Green: Buildings
- Orange: Stuff related to the Main Quest
- Stuff marked (r) is repeatable
XCOM has a habit of creating acronyms that make more sense as the acronym than the actual meaning (if one exists at all).
From the previous game, MEC (Mechanized Exoskeletal Cybersuit) is an acronym to denote what we generally call a "mech". I believe EXALT is an acronym too (from its capitalization), but its name seems to refer more to "exalted" than actually having a meaning to the acronym. Some people have offered that EXALT is named EXALT because they are the "XCOM alternative", but no confirmation on whether that's the case or not.
SHIVs are the only ones I can think of that aren't as blatantly named (a shiv is not a robot but a makeshift knife). But even though it stands for "Super Heavy Infantry Vehicle", we never call them anything else than "shivs".
Even the name XCOM is a shortening for Xeno COMmand. The game very much revels in the use of pseudo-military acronyms and concepts.
The same seems to apply to the suits in XCOM 2.
The E.X.O. suit is an external suit. Rather than mechanizing the unit from the inside like the MECs of XCOM, this is an external variant.
Insects have external skeletons, called exoskeletons... So they called the suit the "exo-suit". Making it into an acronym is just cosmetic, since we will only really use the acronym.
The W.A.R. suit seems obviously named.
Best Answer
When you fail to save enough civvies, you lose contact with the resistance in that area, and will have to reestablish contact by scanning the area again. While contact is lost, your radio tower in the area will not be available. Even after contact is reestablished, you suffer a penalty to the amount of supplies they provide per month.