Gameplay in Armored Core 4 is divided among several modes, where the player can build an AC unit for combat and test its abilities.
- Assemble - In this section, the player builds his AC from the current pool of available parts. This works differently than in previous installments of Armored Core, in that the Shop area is integrated into the garage and can be accessed by pressing square on the PS3. All the parts that are currently available are listed in the garage, whether the players owns them or not. Parts that the player does not own are marked "DATA ONLY".
- Paint - This section is for changing the color of the AC. The player can change the color of any and all elements, except for boosters (same color as core), generator, and FCS.
- Simulation - Simulation is essentially Armored Core 4's version of the Arena found in many previous Armored Core games. A single data pack contains simulation data for one or more enemy Nexts. When a Next is defeated in a Data Pack, the player is given a monetary reward, with an additional monetary award for defeating all the Nexts in a given Data Pack. Other rewards are also available, and include items such as parts for the AC, Memory for tuning, and even new Data Packs. One thing to note about Simulation mode is that the player doesn't need to buy the parts in the schematic to use it. A schematic made entirely out of unpurchased, "DATA ONLY" parts can be used in Simulation without penalty. There is no penalty for losing in Simulation mode, and no cost for repairs or ammunition if the player wins.
- Test - Launches an AC test simulation. As with the Simulation mode, the player doesn't need to purchase the parts in a schematic to use it in a test simulation. By default, there are no enemies in the simulation and the player can add enemies. Targets available include a squad of MTs, a small group of Normals, or a single Next. Only one type of target can be active at a time, and changing target types restarts the test.
- Tutorial - Selecting this option launches the tutorial from the start of the game.
- Schematics - This category is in essence the library of various AC designs. The player can have up to five different sections to keep certain designs separate if desired. There are also pages for enemy designs that are acquired by beating them in the simulator, Company Standard designs, and one reserved for other players designs that have been traded to the player via online. Main, slot A-D, and trade can total up to no more than 100 AC's per save file. To load a design, the player must have at least as much FRS as the desired design uses.
Armored Core 4 has more new features than previous AC games although some of those found in previous AC games were removed. The lockbox from the first AC game up to Last Raven was enlarged to nearly the size of the entire screen and its borders were made invisible. As a weapon's lock approaches the edge of the lock box, its tracking ability decreases, this is most clearly seen when using sniper weapons. AC's will now automatically lock on to enemies when in FCS range instead of waiting for the weapon to be in range. Lock box tracking is now second to melee ability in importance. Melee ability determines how fast a weapon's lock on reticule can track an opposing AC. A heavy weapon with low melee is likely to lose a lock on if a fast AC QB's to the side, while a high melee weapon will maintain its lock on.
The controls for the game have been reworked from the ground up to provide easier and more efficient play. Also, the environment is now affected by AC battles. For example, an AC moving on sand or on the ground will leave footprints, boosting leaves a trail. Some buildings and landmarks can be destroyed. Weapons also possess terra-forming effects. For example, shooting a plasmatic energy bolt at a building causes a small chunk to be removed. Continuous machine gun or assault rifle fire causes bullet holes to appear. Battlefields are now considerably larger, but relatively barren of details unlike previous AC games. The player can now fight on water, unlike past AC games where the player would fall straight to the bottom if contact was made (that is, the player was not given a chance to try to recover).
Other changes made from past AC games include increased weapon damage, the replacement of the heat and overheating game mechanics with Kojima Particles and Primal Armor shielding, greatly increased AP, defense and load capacities, the removal of cannon restrictions on non tank legs, the separation of boosters into categories of main, side, back, and overboost, and ground boosting (and sometimes in the air) no longer consuming energy, but merely causing the energy bar to regenerate more slowly (Generator output no longer stops when boosting, so total drain is a function of output added to boost and weapon drain). A quick boost (QB) function was also added which causes an instantaneous burst of speed. QB is the main method of movement in AC4, and has many analogies to boost movements in older games, such as the QB hop vs boost hop. New techniques include "second staging" and "chaining". Second Stage (or SS) QB can only be used when QB is mapped to a pressure sensitive button, like the triggers on the 360 and PS3 controllers. Pulling the trigger at the correct and steady rate results in a more powerful QB that increases speed and acceleration for negligible drain penalties. Chaining is move that overcomes the latency time between QB's, if one QB is activated but then immediately followed by another in a different direction, the recharge time of the first QB is voided, allowing that booster to be used immediately after the second QB is fired. Overboost is relatively weak, and drains Kojima Particles (KP) when activated. This means that frequent use of OB may leave one's defenses greatly reduced. This led to OB being less popular than in previous games, such as Silent Line.
The world experienced a period of rapid population growth, which put a strain on global food and energy supplies. As populations increased, so did the gap between the wealthy and the poor, and so did the unrest within the population at large. Eventually, violence began to erupt and the governments quickly lost control of their populations as their cities were consumed by terrorism and anarchy. People began turning to corporations, complete with private armies, to keep them safe from the chaos.
In the midst of the meltdown, the world's six most powerful corporate conglomerates decided to do away with national governments and install their own brand of rule and law. They launched a full scale war on the nations of the world, which came to be known as the National Dismantlement War.
Using advanced Armored Core technology, the corporations decimated the forces of the nations and declared victory in less than a month. With the old nations of the world effectively toppled, the corporations set out to work on a new system of government.
The corporations dubbed their new order as the "Pax Economica" ("Economic [or Corporate] Peace", Latin), a system where loyalty and service to the corporations guaranteed food and survival. Under the Pax, however, people were forced into corporate-run colonies and essentially became slaves serving wealthy corporate masters.
Armored Core 4 received mixed reviews. The game received a 7.7 (out of 10) from GameSpot, 5.9 (out of 10) from IGN, 7.3 (out of 10) from Game Trailers, 4 (out of 10) from 1UP.com and 6 (out of 10) from GamesRadar. It has an average score of 67% from gamerankings.
|Game Informer||6.5 out of 10|
|Official Xbox Magazine||6.5 out of 10|
|X-Play||3 out of 5|
|Gamespot||7.7 out of 10|
|IGN||5.9 out of 10|
|Game Trailers||7.3 out of 10|
|1UP.com||4 out of 10|
|gamerankings||67% out of 10|
|GameZone||6.7 out of 10|
|TeamXbox||6.2 out of 10|
- The New Ravens' Ark - American Armored Core community with info on new AC games (designed by a series fan)
- Sega Armored Core website
- Official From Software Armored Core website (some English content)
- ACO Armored Core Online Community website
- Armored Core Parts Conference - A partial list of Armored Core 4 parts.