Mega Man Battle Network 4

MegaMan Battle Network 4, known as Rockman EXE 4 in Japan, is the fourth game of the MegaMan Battle Network series, released for Game Boy Advance in 2003 with two different versions: Red Sun (Tournament Red Sun) and Blue Moon (Tournament Blue Moon). In this game, Lan and MegaMan partake in a series of NetBattle tournaments.

Story
Depending on the version of the game, different opponents and scenarios will occur, as well as Double Souls obtained. In between tournaments, a criminal organization called Nebula will attack. They spread corruption with the use of Dark Chips. These are Battle Chips infused with the power of darkness. They grant immense firepower compared to a regular chip, but spawns a dark soul and does a small amount of permanent HP damage into the NetNavi that uses it.

Meanwhile, an asteroid was travelling through space, heading for Earth. The scientists at NAXA (ANSA in Japan) attempt to divert it. When their laser strategy failed, they decided to send a NetNavi into the asteroid's cyberworld and change its course. The Navi was chosen through an international tournament, which Lan and MegaMan ended up winning.

Nebula attacked again, but MegaMan was able to delete the head Navi and reached the main program operating the asteroid. The program was called Duo and was planning on destroying Earth because of the high levels of dark energy. Lan and MegaMan proved through battle that all people had the ability to conquer their inner darkness, and successfully averted destruction.

Changes from previous games
One great difference here is the introduction of the Emotion Window. Previously, finishing off enemies with a Counter hit with anything, inclusive of the Buster, will yield Bug Frags used to trade for things; Now, you can only counter with non-dimming chips, and doing so will grant you Full Synchro, a powerful state where the next chip you use has double damage. In addition to Full Synchro, there are also Anxious, Angry, and Dark Soul states.

Another thing to note is the removal of the Add Button, and the loss of 2 Custom slots. This has reduced the potential chip-choosing capacity, but has given way to a few things. First, the Soul Unison Button takes the place of the Add Button after MegaMan receives his first Soul. In certain souls, the missing 2 Custom Slots will be filled with other things, like the Shuffle button in Search Soul, and recycled chips in Junk Soul.

The game also introduces Dark Chips. When MegaMan enters Anxious, he cannot use Soul Unisons, but instead can use the Dark Chips, which appear 2 at a time in the formerly missing chip slots. These introduce several harmful effects, but at the same time grant MegaMan immense power and access to special chips that are only usable in Dark Soul.

Style Changes are gone; replacing them are Soul Unisons and Dark Soul. Soul Unisons are unique, version-exclusive transformations that last a limited time, require a chip sacrifice, but give MegaMan special abilities, like charging certain chips for double damage - an ability that was absent with Styles. This added more uniqueness with the transformations MegaMan undergoes.

Navi chip versions have been traded out from the v1/v2/v3 to v1/SP/DS. SP chips are only obtainable by S-ranking Navis without using Dark Chips, and can be powered up depending on how fast you delete the Navi, with the attack maxing out when the Navi is deleted in under 10 seconds. DS chips are obtainable only by fighting Navis under the effects of Dark Soul, or through special mystery data that appears in Black Earth.

The Navicust also has a mild change. Instead of different Styles being able to equip certain coloured parts, MegaMan can equip any coloured part, as long as he does not equip more than 4 colours in the Navicust.

You now can find Mystery Data in battles, too. A single hit from even a Buster shot will destroy the data, and if you keep it intact, you will get bonus data, which can range from rare chips or Bug Frags.

An odd change in this game, though, is the lack of storyline - instead, the player has to play through the story three times to fully collect all the items in the game, while facing increasingly stronger foes as he proceeds through the game. However, most of the data he gets in previous playthroughs gets carried over to the other playthroughs. This has been a major turn-off for most players, resulting in the bad reception the game experienced.

One may also notice that this game has a different art style compared to the previous ones, along with a different town layout for ACDC. This would later carry over into the final two games into the series.

Bosses

 * ShadeMan.EXE
 * GutsMan.EXE\AquaMan.EXE
 * SparkMan.EXE
 * TopMan.EXE
 * FireMan.EXE\NumberMan.EXE
 * BurnerMan.EXE
 * VideoMan.EXE
 * WindMan.EXE\MetalMan.EXE
 * Roll.EXE\WoodMan.EXE
 * KendoMan.EXE
 * ColdMan.EXE
 * ThunderMan.EXE\JunkMan.EXE
 * SearchMan.EXE\ProtoMan.EXE
 * LaserMan.EXE
 * Dark MegaMan.EXE
 * Duo.EXE

Secret Boss
 * Bass.EXE

Trivia
Just before you fight Shademan for the first time Mega Man says, "Leg's go Lan!" instead of "Let's go Lan!"
 * Many textual errors exist in the games' dialogue.
 * Just before Shademan kidnaps Roll in the beginning of the game, he says " I won't hurt a bit", instead of " It won't hurt a bit"
 * When encountering Shademan, he says, "I wish I could fly..." despite the fact that he is floating. It was most likely supposed to be Mega Man's line.
 * What a polite young man she was! (WindMan tournament, Lan's mother says this about Raika)
 * At the beginning of the game when Lan and his father go to Electric Town for the first time, notice Lan's father standing near the juice machines. If you talk to him he will say "There's so many electrical store" instead of "There are so many electrical stores".
 * When you win Red Sun, the announcement will read "taside" instead of "aside"
 * Before you fight Shade Man in the Vampire Robot Lan, Shade Man will have a quick discussion about the dark chip Lan is carrying. When Lan breaks the chip he says "We can't just let an DarkChip like this go free" instead of "We can't just let a DarkChip like this go free".
 * During the Number Man mission when you hand out flyers for the chip shop, you will encounter a Navi that says "What they only hire beautiful emales?" instead of "What, they only hire beautiful females?"
 * The second part of the "WzMonkey" has a section of of the story that says "A evil magician appeared one day in Renice," which should be "An evil magician appeared one day in Renice."
 * In the Mega Man Battle Network 4: Red Sun, after the battle with Searchman, when you are in the waiting room the person comes up to you and says "We should try get along:", Lan says "I don't want really want to get along" instead of "I don't really want to get along".
 * In the section where Lan gets "kidnapped" (the prelims for the Blue Moon or Red Sun), Mega Man says, "It looks live we've been kidnapped", instead of, "It looks like we've been kidnapped".

Anime

 * Just as a side note, the names Red Sun and Blue Moon are the names of the cars used by Protoman and Megaman respectively in the navi car race in Rockman.EXE Stream Episode 7.