These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
As far as operators go, at least in Armored Core 2 the player's operator is shown to become quite attached to and concerned for the player over the course of the game, and AC 4 protagonist/Fiona Jarnefeldt is pretty much canon. Other times though, the operators are just as characterless as the player.
Ensemble Darkhorse - May Greenfield, from Armored Core For Answer. As an entirely optional wingman, May has the bare minimum of characterization and a player can go through the entire game without even encountering her once. However, fans have apparently fallen in love with what little characterization she has, as a cheerful teenage girl who pilots a bright green Mighty Glacier engine of destruction. With a smiley face logo.
How can Nine Ball fire his shoulder cannon without kneeling (ignoring computer cheating)? He/It's an AI, and automatically gets Human Plus benefits.
Why Genobee do the same thing in Nexus? He's an AI too.
The chapter titles in Armored Core 4 are named after Agatha Christie's novels. The default name of the player character in both AC 4 and FA is Unknown, AKA, "U.N. Owen", the alias of the murderer in And Then There Were None, which serves as the title of the final chapter of the game.
Why does Wonderful Body move in the way does? Because he was a Normal pilot and Normals are basically Armored Core's from the older games. (ie: he stops boosting to save energy)
How can the Chief keep firing the Giga Cannon Overed Weapon over and over without fail? because he's also an AI.
How do you end up using Junk Parts at the beginning of Armored Core V, when the intro has you using second generation parts? Since the Story Missions are technically flashbacks, it is highly implied that whatever you were piloting was actually destroyed and you had to make do, starting all over again at the beginning of Order Missions.
Fridge Horror: the last words of the "deranged" raven in the Destroy plus escapee mission " R...raven.....watch...out....YOU..too"... sounds like the ravings of a paranoiac, right? think about em AFTER reaching the endgame, and what happens if you get killed after the corporate wars end..... instead of going back to the nest screen, you see a short cutscene of a computer showing all of your Player characters information, identy records, proof of even EXISTING, being erased....
Game Breaker - Almost every Armored Core game has one (or several).
A recurring one is the Moonlight Laser Blade and Karasawa Laser Rifle. In 4 and For Answer, Kojima weapons.
Reg 1.00 of for Answer has this with SALINE05s, White Glint's multi-missile launcher. Unlike other launchers, these ones have very good homing ability and most of the time, all 8 submissiles will hit the target. Firing them in rapid succession to an enemy NEXT will deplete their Primal Armor, at which the missiles will do double damage. One simply needs to use two of these in Reg 1.00 to easily cut half of the difficulty in Arteria Carpals, Hard mode. Of course, that kind of gamebreakerness is not allowed and since has been nerfed.
In AC 4 and For Answer, Grenade Launchers come into this territory (doing huge damage and area damage, only slightly less useful against the faster enemies), and blades do wicked damage against arms forts.
Also the finger machine gun in Project Phantasma, the has an incredible rate of fire, does massive damage, has a ton of ammo and is extremely light, but in got nerfed in Master of the Arena. They they brought it back in Silent Line.
Chainguns and shotguns in Armored Core 5 both of which can destroy any AC build with ease and take away all the difficulty of the final boss, thankfully the next patch will be nerfing them.
Germans Love David Hasselhoff - Although the Armored Core series is somewhat big in Japan, in North America it's a perennial niche title. So niche, in fact, that Agetec could no longer afford to localize the games after Last Raven and lost the rights to Armored Core 4 to Sega. Sega in turn dropped the license after Armored Core 4 failed to meet sales expectations. UbiSoft then snatched up Armored Core for Answer, but it failed to meet expectations as well... Are you noticing a pattern yet?
It would help if they could advertise for it a little more...
Armored Core 5 is now being localized by Namco Bandai.
In a reverse example, if any comments on Niconico are to go by, Japanese players laughed at the inept translation errors that was abound in Armored Core: for Answer, but they absolutely in love with the full range of English voice cast, whether it's GA rep's hammy voice, to Shamir Ravi Ravi's murderous voice, and of course, the various accents that Canis, Dario Empio and Do Su employed. They don't even seem to be bothered by the massive change in voice type that Ay-Pool has.
Harsher in Hindsight: Poor, poor RD. His only wish is to survive the whole big conflagration that is the Resistance vs. Father war. His big sister figure makes fun of him, his allies only think he's useful because of his sixth sense, and nobody pays him any attention. Small wonder when the Corporation offered him a chance of survival and an AC of his own while telling him that he's special, RD promptly tries to kill you. In the end, after you defeat him for the last time:
Play the Game, Skip the Story: The only way to understand any story in this series is through the messages that are sent to you when you complete certain missions. Too bad that you'll be busy bypassing this part in favor of setting up your AC for the next arena fight or mission. It doesn't help that the story in the series is somewhat mediocre, and when the story does get good, From Software decides to Retcon it in favor of another game. Adding insult to injury, two of the games don't even have a story at all.
Recycled Script: For a while the background plot to the games was getting more creative, but at point they just started to recycle the same plot from the first game over and over for every single game.
As of Verdict Day, this is actually a plot point. Turns out that V and Verdict Day are the same universe as 4 and For Answer, and humanity keeps blowing itself up ala Turn-A-Gundam.
Screwed by the Network: On the English front of AC V which has two different servers for the game being US and EU, this is bad because the series doesn't sell as well as it does in Japan and the player base is starting to drop due to the game being three patches behind the Japanese version of the game, having multiple game breaker's and having Unstable Equilibrium kick in.
It could be handwaved by having their living quarters inside the portions you are supposed to attack. But even then, I highly doubt that those areas are big enough to house 10 million people total.
When you lose an online match in 5 you bail out of your AC and fly around with a jump pack which is fine, but you're so much bigger than the cars that sit idle on the maps. Even worse is that when you touch them they explode.
At least From knows this since they added some silly models for them like a ninja holding onto a raven (Ken?) and a mini Nineball Seraph.
Let's see...Stinger from Project Phantasma, The Frighteners from AC2, the Massive MT and the Bonus Bosses from Another Age, Leviathan and Ofanim from AC3, Big White and IBIS from Silent Line, Agraya, Genobee and Nine Ball from Nexus, Nine Ball from Ninebreaker, Nine Ball from any game he appears in, Zinaida (On the Last Raven path) and the Pulverizers from Last Raven, take your freaking pick.
For some players, ANY AC of relatively equal quality is That One Boss.
Sherring in AC 4 isn't exactly a pushover, either.
Nineball. Seraph. Yeah it's the Final Boss, but it qualifies due being a huge Difficulty Spike above anything you fought before (your armor is actually restored before the fight with it unlike everything fight in the game, that's how hard the developers realized it was). No matter how you built your AC, this thing's machine gun arms and laser blades can literally kill you in seconds, and it's hard to avoid its missiles as well. Compounded by the lack of cover and your inability to match his speed and flight ability. There's no real strategy for beating it, all you can do is shoot at it and try your best to avoid getting killed. Much less so in Another Century's Episode R, however.
Chief 'piloting' Exusia in 5 who is fast enough to easly kill the standard AC build in a few passes if you give him room to breath.
White Glint in Verdict Day. Missiles? Check. Fast and dodges a lot? Check. Primal Armor field so you can't hit him? Check. Assault Armor and a massive explosion? Check. A 2nd phase that you take damage wherever you go and it starts to dodge even more?! Check. And if that wasn't enough a bonus version of it exist somewhere and it's anyone's guess how hard it is.
How bad is the Bonus version? It now starts using it's VOB so it's even faster has a laser attached and divebombs the area.
Missions set in fog will sink your mission rating due to the time it takes to complete them.
Same with the above that one boss entry with any AC/NEXT being one the same goes for missions.
Occupation of Arteria Carpals. (It's That One Boss x4 or 5) Well, you deserve it, you bastard.
Arms Fort Answerer too, unless you know what you are doing.
White Glint the first few times you fight the bastard. Every time after that? Cakewalk.
AF Cabracan. Not because of the difficulty (it's a piece of cake), but the Land Mines and the Drones. It takes most of your ammo to take half of them out if you are using any guns, and you can forget about explosives because of their mobility. Oh, and they can walk through walls, apparently treating the sand you stand on as though it weren't even there, and making it impossible to hit them until they resurface. They are not designedwith that ability in mind. They are also fairly nimble and airborne, making swords very difficult to use.
Sol Dios Orbit in For Answer... unless you're playing on hard mode.
Any mission in Verdict Day that involve Autonomous arms. Unless you have scanned all the arms before hand and prepared for such, you will have an arm that is resistant to your weaponry.
Win Back the Crowd: Verdict Day for the western fanbase as it has a better setup online, a merged US/EU server, better part selection, increased energy output across the board, Hardcore mode, White Glint and combining V/VD and the 4/4A continuities together. Only time will tell if it holds up.
Also applies to every expansion as it adds more to each engine, 4 to For Answer is a good example.