Setting
Ace Combat 3 is set in the series' fictional universe of Strangereal, where Earth has entirely different nations, geography, and history. Specifically, Ace Combat 3 is set in a partially-noncanonical cyberpunk near future rendition of Strangereal, in which the world's governments have been effectively superseded by multinational megacorporations that wield massive political, economic, and military strength, the two effective "superpowers" being General Resource Limited and Neucom Incorporated ("Neuwork" in the international versions). Both megacorporations, locked into a fierce power struggle in the continent of Usea, eventually declare direct corporate warfare against each other in 2040, prompting the Universal Peace Enforcement Organization (UPEO), an international peacekeeping force with dwindling influence, to respond to stop the Intercorporate War from worsening. A major part of the 2040 rendition of Strangereal is the "Electrosphere", a fictional version of the Internet; in the 2030s, advancements in technology made uploading one's consciousness to the Electrosphere possible, causing a rise in transhumanism as well as Ouroboros, a transhumanist terrorist group based out of the airship Sphyrna that believes humanity can ascend to a new plane of existence by uploading their consciousness to the Electrosphere.
Characters
The characters of Ace Combat 3 include peacekeepers, mercenaries, company men, diplomats, scientists, news presenters, and terrorists. The game is played through the perspective of a silent protagonist named Nemo. The main cast is composed of fighter pilots affiliated with either a peacekeeping organization, one of two rivaling private military companies, or a group of revolutionary terrorists. The player, allies, and enemies, may change their allegiance over the course of the game. NPC characters interact with the player via videophone calls, videomail messages, and radio transmissions during gameplay.
Japanese version
In 2040, UPEO deploys their Special Armed Response Force (SARF), a fighter squadron led by Commander Park that includes Nemo, the player character, and Rena Hirose, a prodigous flying ace, to respond to incursions by Neucom in no-fly zones. Accusing UPEO of supporting General Resource, Neucom launches a preemptive strike on General Resource, initiating the Intercorporate War. To prepare for combat, Nemo undergoes aerial training from General Resource's top ace, Abyssal Dision. Impressed by Nemo's skills during a subsequent mission, Dision asks them to defect to General Resource. If Nemo stays with UPEO, they begin to fight General Resource, who are attacking Neucom. Nemo is later assigned to escort Gabriel William Clarkson, UPEO's Delegate, who is traveling to a conference to mediate a ceasefire, when Commander Park suddenly claims Clarkson is a Neucom spy and orders Nemo to shoot down Clarkson's plane. If Nemo spares the plane, Neucom offers Clarkson protection, and Nemo transfers to Neucom. If Nemo or Rena kills Clarkson, they remain with UPEO.
It is ultimately revealed that the conflict was orchestrated by Ouroboros, led by Dision, who had secretly been "sublimated" into the Electrosphere and made into an AI copy following a cover-up assassination attempt by General Resource aimed at destroying the mind-uploading technology he was testing. Commander Park is also revealed to be a member of Ouroboros who was using SARF to inflame the conflict. If Nemo stays at UPEO, the player, along with wingman Erich Jaeger, eventually break away from UPEO to bring back Rena, an ally who has joined Dision, and to defeat Commander Park, who has allied himself and UPEO with Dision's coup d'état. If Nemo chooses to leave UPEO for General Resource or Neucom instead, different endings will result, in which Nemo either defects to Ouroboros or remains with the corporation and ensures their victory. Regardless of the player's choices, Nemo shoots Dision down in every ending.
After all five endings are completed, scientist Simon Orestes Cohen reveals that Nemo is actually an AI program that Simon has been training to eliminate Dision to avenge the death of his love interest, fellow researcher Yoko Martha Inoue, who was the target of the same cover-up that killed Dision.
International version
Due to development constraints, the plot in the international versions of Ace Combat 3 was heavily cut down, with characters, backstory, and its multiple endings being completely removed. This version lacked voice acting and the majority of animated cutscenes present in the Japanese release, with the non-gameplay story elements being told through text slideshows between major missions.
Nemo, a human pilot flying for UPEO, deploys to fight off Neuwork's attacks on General Resource. It is eventually revealed that Ouroboros precipitated the conflict, led by a rogue AI developed by Neuwork codenamed "Aurora". Nemo eventually fights and defeats Aurora inside the Electrosphere, bringing the AI threat and the war itself to an end.
