The fourth game in the Mega Man X series (and the sequel to Mega Man X3), the game is the first to be built for 32-bit consoles (allowing them to use a new higher-quality art style, higher-quality audio, and a game saving system). Mega Man X4 also features animated full-motion video cutscenes and separate campaigns for both Mega Man X and Zero (who now has a different close-ranged combat style with his Z-Sword).
Set in 21XX, shortly after the events of Mega Man X3, a new Reploid anti-Maverick military force has risen (the "Repliforce") led by the powerful Reploid, General (and his second-in-command, Colonel). When massive floating city Sky Lagoon crashes down to Earth (killing millions of civilians) and Repliforce is believed to be behind it (soon regarded as a force of Mavericks), X (teamed up with rookie Maverick Hunter Double) and Zero (teamed up with Colonel's kind-hearted sister, Iris) must investigate the Repliforce's plan to build a utopian space station (believing it to be used for a more sinister purpose).
The game was later released for the PC in Japan (on December 3, 1998) and North America (sometime in 1999) and is included in the Mega Man X Collection compilation for the PlayStation 2 and GameCube (released on January 10, 2006).
The gameplay for X is similar to the previous games in the series; X has his X-buster that can be charged up to shoot out a powerful projectile, he can climb on walls, and has a dash move. When bosses are defeated, X can inherit their powers in the form of a weapon with limited ammunition. X also has armor upgrades - Helmet, legs, body armor, and X-Buster - that are found in four of the eight levels; they can upgrade X's power for the X-buster, and others can give him special abilities that he never had.
Zero is similar to X in terms of basic mechanics (Dash and climb), but differs greatly in terms of combat. Zero is more up close melee style, he also has no projectile attacks (With the exception one that is earned by Storm Owl). Zero has no armor upgrades - it's partly due to the fact the armor upgrades are not compatible to Zero (It was explained in Mega Man X5). When a boss is defeated, Zero learns a new technique instead of a new weapon - he also has no limit to how many times he could use his newly learned techniques.
Other upgrades can be found in each of the stages. Such as heart containers, that can increase the health bar; and energy capsules that's use to store extra health. In the previous games, the player can hold up to four energy capsules, but in Mega Man X4, only two are found for the health bar and a third one is use to refill a weapon's ammo.
- Helmet: The helmet upgrade allows infinite energy for all of X's weapons.
- Legs: The leg upgrade allows X to hover in the air for a short amount of time.
- Body Armor: The armor upgrade gives X a new ability known as Nova Strike - it's a powerful air-dash move. The way the Nova Strike is done is by filling up a meter by taking enough damage - it's similar to the G-Crush armor from Mega Man X2.
- X-Buster: For the first time in the X series, Mega Man X4 allows the player to give a choice of two X-Buster upgrades. One of them lets X charge up his X-Buster up to four times. The other version gives the X-Buster a fourth level when charged up.
The most well drawn level in the game, the jungle level has X or Zero going through streaming water while battling javelin wielding mavericks that can shoot spears from their backs in eight different directions. Other areas contains large gaps with a waterfall raining down in between with falling logs that are used as platforms for X or Zero to get through. Mechanical bee hives are also present - they can generate robotic killer bees. Robotic snakes are also found - they can sneak up on X or Zero while crossing through trees.
A snowy level that's filled with mechanical polar bears that have the ability throw out sharp ice blocks. Other sections have X or Zero going through spiked floors with sliding platforms that will disintegrate in a short period of time; on the platforms, are mavericks with skiing gear on. The other section of the stage is filled with frozen blocks that have bombs or the little helmet mavericks frozen inside. And the last sections of the stage has a bird that can change the scenery by freezing everything.
All of this level is done via "land chaser" - a hover bike that can shoot out projectiles. It's a fast moving stage that has pipe bombs planted on the ground and other mavericks on land chasers as well; Jet Stingray will appear in the middle of the stage to shoot out some ground hunters to try to stop X or Zero. The land chaser has the ability to dash on the ground or in mid-air.
Not much platforming in this stage, but there's lots of shooting involved. X or Zero are on top of a train going through waves and waves of mavericks - some of them are equipped with hand guns and can throw grenades. At one point one in the stage, X or Zero will be in control of a mech suit that's equip with a laser sword that can do some heavy damage.
Probably the most creative stage, Cyber Space contains yellow spheres moving along slowly across the stage; if unable to avoid it, the sphere will suck X or Zero to the center of it and do some damage. Portals will also appear with mavericks coming out of them. While X or Zero is going through the stage, they will be timed, if they make it through a section of the stage quick enough, they will be ranked. If they get the highest ranking (S rank), they will go through a short area that contains a heart container, energy capsule, or an armor upgrade.
At the beginning of the stage, X or Zero will go through a flight of stairs that will actually rotate 360 degrees while moving along (kind of giving the player the sense that it looks like 3D). Other areas have X or Zero going through short tunnels with mavericks with powerful drills on top of the tunnels ready to destroy the place as soon X or Zero crosses through. Another part has X or Zero moving upwards through a small corridor filled with hovering mavericks that shoot out projectiles.
In this stage X or Zero will be on top of an aircraft going through laser shooting canons, giant mavericks that shoot out missiles, and even more gigantic canons that can shoot out devastating lasers. Another mech suit will be present for X or Zero to take control, but this one is different than the one that was found in the Slash Beast stage. This mech suit can hover in mid air and can shoot out charged up projectiles.
A lava filled stage that contains sections that has X or Zero going through falling rocks, giant fireballs coming out of the ground, and platforming sections that has fireballs falling through in between the gaps. But some of the platforms are not safe to be on, some of the fireballs will shoot out from the ground and will go right through one of the platforms that X or Zero is on.
Name: Frost Walrus
Description: He protects the weapon which lies deep within the snow base.
Level: Snow Base
Weapon: Frost Tower (X). Hyouretsuzan (Zero).
Objective: "We've discovered a hidden base. Halt production of their new weapon."
Name: Jet Stingray
Descrption: He destroyed the city and escaped to the Sea.
Level: Marine Base
Weapon: Ground Hunter (X) Hienkaru (Zero)
Objective: "Repliforce decimated the city and left. Pursue them aboard a land chaser."
Name: Slash Beast
Description: He defends the Military train to protect the supply of goods.
Level: Military Train
Weapon: Twin Slasher (X) Shippuuga (Zero)
Objective: "A military train is moving supplies. Cut off Repliforce's supply route.
Name: Web Spider
Description: He protects the secret weapon of the jungle.
Weapon: Lighting Web (X) Raijingeki (Zero)
Objective: "Infiltrate enemy-occupied jungle and destroy the weapon under construction.
Name: Spilt Mushroom
Description: He occupies the laboratory and attacks anyone who visits there.
Level: Bio Laboratory
Weapon: Soul Body (X) Ruuenbu (Zero)
Objective: "The abandoned lab is now operational. Investigate and destroy the lab.
Name: Cyber Peacock
Description: He lives in cyber space and he wants to destroy the Network System.
Level: Cyber Space
Weapon: Aiming Laser (X) Rakuhouha (Zero)
Objective: "A bug has corrupted the network. Dive into Cyber Space and exterminate it."
Name: Storm Owl
Description: He left with a space fortress to conquer the air.
Level: Air Force
Weapon: Double Cyclone (X) Tenkuuha (Zero)
Objective: "The Repliforce ship has taken off. Pursue and blast it out of the air."
Name: Magma Dragoon
Description: He betrayed the irregular hunters and hid himself in a volcano.
Weapon: Rising Fire (X) Ryuenjin (Zero)
Objective: "Dragoon of the 14th unit is a traitor. Locate and bring him back to hunter HQ."
In 2005 Capcom released a 5-disc box set called Capcom Music Generation Rockman X1~6. It contains the original music of Mega Man X through Mega Man X6 as well as some unused tracks. Mega Man X4 tracks span the entire third disc and the track listing is as follows:
|4.||OPENING STAGE X||2:02|
|5.||OPENING STAGE ZERO||1:39|
|8.||WEB SPIDUS STAGE||2:49|
|9.||CYBER KUJACKER STAGE||2:33|
|10.||STORM FUKUROUL STAGE||2:21|
|11.||MAGMARD DRAGOON STAGE||1:58|
|12.||JET STINGREN STAGE||1:54|
|13.||SPRIT MUSHROOM STAGE||2:44|
|14.||SLASH BEASTLEO STAGE||2:47|
|15.||FROST KIBATODOS STAGE 1||2:14|
|16.||FROST KIBATODOS STAGE 2||2:35|
|18.||STAGE CLEAR X||0:11|
|19.||STAGE CLEAR ZERO||0:11|
|20.||GET A WEAPON||0:39|
|21.||STAGE SELECT 2||0:45|
|22.||FINAL WEAPON STAGE 1||1:33|
|24.||FINAL WEAPON STAGE 2||2:50|
|34.||BETRAYAL OF DOUBLE||0:31|
|36.||MEMORY OF PAST 1||0:39|
|37.||MEMORY OF PAST 2||0:22|
|38.||COLONEL VS ZERO||0:24|
|39.||PAST OF ZERO||1:42|