!''Armored Core 4 / for Answer'' as the deconstruction of the series.
This troper might be over-analyzing. Both are not particularly impressive pieces of video games, but some points keep sticking out when compared to previous installments.

!!The corporations and their limits
Corporate warfare has always been with Armored Core (until ''V''), but all are made through hired mercenaries which is then controlled by single, independent agency. (Ravens' Nest, Nerves Concord, Global Cortex) The Ravens freely changes between clients, the fact that has been widely accepted in-universe.

But here, the corporations ''are'' the rules. The colonies now have explicit affiliation to a certain group and those inside are forced to work like slaves. The Collared originates out of agreement between all firms. Irregulars ([=LYNX=] who refuse to get into Collared) and independent states actively get squashed on basis. There is no middle line. The entire Earth has become the ultimate battlefield.

''Last Raven'' has forced players to take sides before, but never as a ''status quo'' on global scale like this.

!!The [=NEXT=]s and their overwhelming power
Armored Core portrayed [=ACs=] as a weapon akin to tanks or fighter jets, often deployed against a small squad of [=MTs=] or a small base. Units are ground based with limited flight time. Maneuverability is achieved by continuous boost, or a short burst in a direction when dodging is required, all of which drains from energy pool. Cue the [=NEXTs=].

[=NEXT=]s in [=AC4/fA=] are capable of instantly breaking sound barrier given right setup and a mere thought (thanks to [=AMS=] hard-wiring pilot nerves with the [=AC=]) Massively increased power output allows for [[FlashStep QB-chaining]] and [=AC=] builds with unlimited flight. The development of Kojima Technology results in ''regenerative'' energy shielding and highly damaging weapons that can easily annihilate small cities in a few minutes (sometimes ''in a single shot''). Some colony employs a single [=NEXT=] as their sole and only defenses against armies of Normals. Companies are justifiably paranoid when it comes to Irregulars as if they were loose nukes; unlike registered [=LYNXs=] they can't predict where all those firepower will land on next.

Most importantly, continuous usage of [=NEXT=] pollute its surrounding with harmful Kojima Particle contamination. Which brings us to the next point;

!!The settings
Most Armored Core games were about the world going through some sort of progress. The first game and ''3'' are about civilization trying to rebuild itself. ''2'' is about expanding to Mars. Even ''Last Raven'' is about bringing in ideal world [[MultipleEndings for each faction]] or about the creation of ultimate Raven, if you wanted to look at it that way. Even if the world have been ravaged by war, there is still room for hope.

''Armored Core 4'' universe however presents us with a story of CrapsackWorld in the making. Everything and everyone continuously [[SlowlySlippingIntoEvil Sliding Down The Slippery Slope]]. The only way humanity can continue to survive is to carry on destroying in one way or another. The developers choose to drive this point home by;
** Giving bits and hints into personal lives and history into most individuals and locations, as opposed to putting the Raven in detached position from the world they live in. Emphasizing the loss of humanity. The most glaring example of this would be the PlayerCharacter in [=AC4=] and his hometown Anatolia.
** Heavy usage of ColorWash combined with emptiness of most locations in contrast to more vibrant and well developed cities / military bases.

Overall, the world of [=AC4=] is the world of Armored Core but without restraints, partly due to limitations posed by game console hardware of respective era, where core elements of the series are realized to the fullest. It brings up power fantasy the series has built so far and mercilessly tears it down.