Mega Man Network Transmission

Mega Man Network Transmission, known in Japan as Rockman EXE Transmission (ロックマン エグゼ トランスミッション), is a Mega Man Battle Network series video game developed by Arika and published by Capcom for the Nintendo GameCube console. The game's story takes place between Mega Man Battle Network and Mega Man Battle Network 2.

Story
One month after the defeat of WWW, Lan Hikari and MegaMan are enjoying the peace they helped bring about, interrupted only by news of the new "Zero Virus" spreading around the net, a virus that targets Navis and affects their functions. Soon, Lan receives an e-mail from Mayl Sakurai, telling him that Roll hasn't returned yet from her errand. Setting out to find her, MegaMan discovers her route is blocked by a fire caused by FireMan. MegaMan defeats FireMan, only to discover that his owner, Mr. Match, isn't responsible for his actions, which only happened after he'd installed a vaccine for the Zero Virus. Lan's father explains that FireMan's actions were caused by the vaccine Match used, which was a fake (as no real vaccine had been created yet).

Lan and MegaMan set out to discover the vaccine's distributor, who turns out to be StarMan. Realizing the jig is up, StarMan retreats, but MegaMan's pursuit is interrupted by a call from Dex Oyama, who had also used the phony vaccine, resulting in GutsMan going on a rampage. MegaMan manages to beat GutsMan without deleting him to halt his rampage. Lan's dad then tells Dex to pull GutsMan back into his PET and turn it off until a cure can be developed.

MegaMan and Lan then go and help out their friends, also affected by Navis with the false vaccine, at Yai's house (NeedleMan), the Waterworks (IceMan), Higsby's store (BrightMan), and the bank (QuickMan) before they turn in for the day.

The next morning, the two begin a search for Zero Virus information, despite Eugene Chaud telling him to keep out of it. After fruitless encounters with ColorMan and ElecMan, MegaMan finds himself infected with the Zero Virus. Desperate for information, the two begin searching Zero Account, an abandoned sector of WWW data used for creating the Zero Virus. MegaMan makes his way through Zero Account, defeating SwordMan, GravityMan and StarMan, and helping an infected ProtoMan. During their travels, they encounter a mysterious data source file which they send to Lan's father, as well as receiving a real cure to the Zero Virus.

Eventually, they encounter Zero, the source of the virus. Zero reveals himself as a living virus who spread the virus to gather information and eventually evolved into more of a NetNavi. Lan and MegaMan feel sorry for Zero, but are forced to defeat him in combat. ProtoMan steps to deliver a fatal blow, but Lan's father manages to use the source file Lan found of Zero's code to seal Zero's virus creation, allowing him to live as a normal NetNavi. Unfortunately, the real mastermind, the "Professor", reveals himself, stating the whole scheme was to use the fake vaccine profits to resurrect the Life Virus and initiate the war Wily had wanted to start.

With the world in a panic, Lan finds himself nervous that they can't defeat the Life Virus with Hub.BAT, but a quick talk from Dex perks him back up and the two head for the Undernet, the most likely place the Life Virus could be hidden. Unfortunately, an auto-jump trap sends them to SciLab instead. Realizing they need the AuthCode to get past it, the two search the WWW Metroline and the Legendary WWW area, guarded by ShadowMan and PharaohMan respectively, and find the information needed to get past the trap. After an (optional) duel with ProtoMan, MegaMan heads into the Undernet.

After fighting past a firewall and Navi doubles, MegaMan ends up attacked by viruses, but his friends arrive to hold them off while MegaMan finds and defeats the Life Virus. The Professor prepares to retreat, but is cornered by officials, who used information from the Zero Virus and Zero to track him down. Zero then sets off to explore the Cyberworld, and Lan and MegaMan return to enjoying the peace while ShadowMan and his owner, Dark, consider an offer from Gospel.

In an optional encounter or boss, MegaMan finds himself against Bass, but can't do much more than tear his cape a bit. Defeat seems imminent, but Bass decides to spare their lives for the time being.

Bosses

 * FireMan.EXE
 * GutsMan.EXE
 * NeedleMan.EXE
 * IceMan.EXE
 * BrightMan.EXE
 * QuickMan.EXE
 * ColorMan.EXE
 * ElecMan.EXE
 * SwordMan.EXE
 * GravityMan.EXE
 * StarMan.EXE
 * Zero.EXE
 * PharaohMan.EXE
 * ShadowMan.EXE
 * ProtoMan.EXE (Optional boss)
 * Firewall
 * Life Virus R (Final boss)
 * Bass.EXE (Secret boss)

Trivia

 * This is the only Mega Man game to be released exclusively for the GameCube.
 * This is the first Mega Man Battle Network game to introduce an Mega Man X series-based NetNavi, Zero.EXE.
 * Some enemies and elements of the game are references from the classic Mega Man series, such as the attack pattern of the multiple Spikey enemies, the various Sniper Joe enemies, the lasers in QuickMan.EXE's stage, and the rail lifts in ShadowMan.EXE's stage.
 * As well as that, FireMan.EXE's music is a remix of his classic counterpart, and PharaohMan.EXE's stage BGM has a small portion reminiscent of his classic counterpart.
 * According to Yuji Ishihara, Mega Man Network Transmission was originally going to be released with a special PET-shaped GameCube controller. Prototype images can be seen in Mega Man Battle Network Official Complete Works.
 * The voice acting is exclusively in Japanese with English subtitles.
 * In the English version, voice clips where Lan says "Rockman" are removed.
 * In the Japanese version, leaving the title screen idle for some time will show the first opening from the anime.
 * Interestingly, although this game's story is between the first and second games, the PET used in this game is based off the one introduced in Mega Man Battle Network 3.