Mega Man Zero 4

Mega Man Zero 4, known in Japan as Rockman Zero 4 (ロックマンゼロ４), is the fourth and final game in the Mega Man Zero series for the Game Boy Advance, released in 2005 and made by Capcom and Inti Creates.

Gameplay
The gameplay remains the same as that of its predecessors: Zero must navigate through difficult obstacles while fighting Mavericks.

The customization system from Mega Man Zero 3 returns in a more complex, detailed form. Players can still mix and match different chips for Zero's body to modify and improve his abilities; however, instead of obtaining completed chips from Bosses, Zero must instead create chips using parts dropped by enemies. The Elemental Chips, a mainstay of the series and technically a part of this system, are omitted. If two to four parts are incorrectly mixed together, a Junk part is created, which has no apparent use other than to make the Junk Armor. In turn, when all pieces of the Junk Armor are equipped and the cyber-elf is deactivated, Zero's attack power will drastically increase in exchange for halving Zero's defense (simulating the Proto Form from previous games).

Zero does not gain any new main weapons during the course of the game. This time, he starts out with the Z-Saber and Buster Shot Gun again, along with a new weapon, the Z Knuckle, a powerful weapon chip implanted in Zero's arm that allows him to punch enemies with incredible physical force. In addition, when Zero defeats an enemy with the Z Knuckle, he can steal that enemy's weapon and use it as his own, though he can also toss it away if the player wants to discard it or the weapon runs out of ammo.

The Cyber Elf system is simplified this time. as Zero uses just one, but very powerful, upgradable Cyber Elf named Croire (the default name is given by Alouette; the player can choose another name by talking to Resistance members). Depending on the name, her development will differ. This Cyber Elf can be upgraded by feeding her E-Crystals. The player may choose to talk to her for encouragement or hints at item recipes. In addition, the use of the Cyber Elf no longer penalizes the player for its usage, except for when Croire's total level is set above that of the current max level. Though akin to a Satellite Elf, this one mimics abilities of other elves, allowing her to augment Zero's abilities of the Hacker, Nurse and Animal kind.

New to the series is a Weather System that affects the levels that Zero travels through. Depending on the weather, the terrain can be affected in a number of ways, such as removing, obscuring, or adding new obstacles. Levels that have a flashing border indicate a harder experience, whilst non-flashing ones will be easier. This can be changed right before the mission briefing. Playing on a harder stage may amplify the boss's strength as well as grant them the use of their EX Skill. Instead of finishing at S or A rank like previous games, completion of a level in its harder form will grant Zero an EX Skill, while easier ones will not, and will also result in a penalty at the end of a mission.

A new Easy Mode is exclusive to this game. Energy Crystals are non-existent, and Croire starts out at Max Lv. 15 with Lv. 5 abilities, but cannot level up any further. In addition, all levels are automatically set to 'Easy', thus no EX-Skills can be obtained. Lastly, instant death hazards are weakened (for example, Spikes and lava only damage Zero slightly, and the player cannot die from falling off screen, as Zero will simply float back up).

The game also has a Hard Mode, but it is now integrated into the options of gameplay when unlocked, instead of holding "L" while starting a new game. In this mode, Zero starts out with his "Black Armor", Croire is still available, though she cannot be raised, and all levels are automatically set to 'Hard', forcing the player to enter each stage in bad weather, even though EX Skills cannot be learned.

Ultimate Mode can be unlocked by collecting all enemy parts in the game and fully upgrading Croire. In this mode, the player can utilize all of Croire's abilities right from the start, and without any penalties. Again, this can be unlocked as a gameplay option, and the player does not need to hold "R" when starting a new game.

Like the previous game, there are also seven minigames that can be unlocked once certain criteria are met. They are as follows:
 * Lumberjack - Beat the game with an overall S-Rank.
 * Lava Surf - Beat the game with a complete database.
 * Busy Basket - Beat the game once on Hard Mode.
 * Slam Harvest - Beat the game under one hour.
 * Plant Panic - Beat the game without feeding your Cyber Elf any E-Crystals.
 * Elf Chase - Beat the game without using any recipes.
 * Energy Lab - Surpass the high score on all the other mini-games.

Most of the mini-games involve Zero's Z-Knuckle and the weapons it acquires.

Story
Even with the death of Omega in the last game, Dr. Weil is still the undisputed leader of Neo Arcadia. With his iron fisted rule, both humans and Reploids alike are now under oppression.

The game begins with a group of humans that are escaping what was once their home, being chased by a new type of enemy soldiers, the Variant. Zero and the Resistance join the chase, fighting off the Variants and saving the humans. Ciel and Zero meet the leader of the Caravan, Neige, who tells them about the current situation in Neo Arcadia, and that she is now leading her group to Area Zero, where a human settlement was established.

The Resistance convoy follows the Caravan into Area Zero. Exploring the habitat, Zero soon encounters the Einherjar Eight Warriors and their leader, Craft. Through them Zero learns of Ragnarok, a military operation where Weil plans to obliterate all inhabitable places like Area Zero so that humans would stop running away from Neo Arcadia. The Einherjar and Craft are the ones who will execute this plan, thinking the humans are foolish to even think of running away from Weil's rule.

After defeating four of the Einherjar, Zero must once again come to the defense of the humans when the Settlement itself is under attack. Craft himself led the attack force, his target being Neige, revealed to be an old friend of his. Even though Zero defeated Craft, he was able to kidnap Neige, and take her to a prison where Craft believes Neige will be safe as Operation Ragnarok continues. Zero attacks the prison and rescues Neige.

Once the rest of the Einherjar are defeated, everyone discovers that this is all just a ploy: the Einherjar were merely a diversion just so Dr. Weil can complete Ragnarok, a satellite in orbit that can destroy anything in its sights with its powerful laser. However, Craft, aboard Ragnarok, announces his rebellion, planning to kill Weil with Ragnarok, even if it means destroying Neo Arcadia! Ciel quickly sends word to the Resistance back at the old base to assist in evacuating the city, while Zero teleports into Ragnarok to stop Craft. However, Craft manages to open fire before Zero can reach him, destroying Neo Arcadia in a single blast. Zero defeats Craft, and with Weil seemingly dead after Craft's attack, the crisis finally appears to be over. Except...

To everyone's horror, Ragnarok was still fully operational. And worse, it's now descending to Earth, preparing to crash into Area Zero. With the help of Neige, Zero was able to access the Teleporter Base, then Cyberspace, and finally, gain entry to Ragnarok once more.

Fighting through Ragnarok's defenses, including the rejuvenated Einherjar, Zero reaches the Core. There he discovers Weil is in fact still alive, having been literally immortalized (via uploading his brain waves into a constantly regenerating armor) as punishment for his evil deeds in the past. Wanting to witness firsthand the destruction of Area Zero, Weil maneuvers the station itself, knowing that he will survive the crash because of his regenerative armor. Zero engages the madman in two battles, and in the process destroys Ragnarok, saving Area Zero and everyone in it.

In place of a celebration, the entire Settlement (now occupied by both humans and Reploids) has gone quiet, having cast Zero's survival into doubt. Seeing him as an example, the two sides have now agreed to work together to maintain the peace that Zero created. Ciel believes that Zero will return to them one day and will be waiting for him.

...but as dawn arrives, somewhere in the desert, in a crater where some of Ragnarok's pieces fell, there is a shattered red helmet that lies forlornly in the sands.

Bosses
Eight bosses (Einherjar Eight Warriors):
 * Fenri Lunaedge
 * Heat Genblem
 * Mino Magnus
 * Noble Mandrago
 * Pegasolta Eclair
 * Popla Cocapetri
 * Sol Titanion
 * Tech Kraken

Other bosses:
 * SubDesert Core (First boss)
 * Carnage Force 0
 * Craft (Fought twice)
 * Hell the Giant
 * Randam Bandam
 * Cyball
 * Dr. Weil (Final boss)

Trivia

 * Although called Mega Man Zero 4, this is one of only two games in the entire metaseries that doesn't feature any Mega Man incarnation, considering that Zero was originally a side character.
 * "Belief" is a prominent theme with Zero throughout the game:
 * It is the translation of the default name (Croire) of the Cyber-elf given to Zero by Alouette.
 * After his second battle against Craft, Zero expresses that he believes in the humans that his friend trusts, making the defeated Einherjar commander see the error of his ways.
 * It is expressed twice in Zero's final (and famous) lines: once to show who he's fighting for, and the second a direct message to Ciel.
 * In the final sequences of the game, Ciel openly believes that Zero is still alive against all the odds.
 * With the release of this installment, this is the first Mega Man series to ever be given an official conclusion.
 * It is also the only series within the robots continuity to be given a conclusion, as the Mega Man Battle Network and Mega Man Star Force series are in an alternate continuity altogether.
 * The final mission, where Zero must stop Ragnarok from crashing into Earth, is similar to the final mission of Sonic Adventure 2. In that game's final mission, the player must stop the Space Colony ARK from crashing into Earth. The "colony falling onto the Earth" theme also is a part of the plot of Mega Man X5. Chikao Ohtsuka also voiced both main villains/instigators of it as well (Dr. Weil and Professor Gerald Robotnik, respectively, though the latter was nothing more than a transmission).
 * Mega Man Zero 4 is the only game in the series where the player can talk to people besides the Resistance soldiers. They are the humans in the settlement.
 * This is the only game in the series with a Boss Rush in which all eight bosses are fought in a single "hub" room, mirroring previous games from the original Mega Man and Mega Man X series.
 * Like the first Mega Man Zero game, the boss theme "Nothing Beats" is used for all but the final boss battle, whose theme, "Falling Down," and Craft, whose theme, "Power Field", are completely unique.
 * Unlike the North American GBA version, the Mega Man Zero Collection uses the Japanese vocal ending for the game.