Mere minutes before the signing of the non-aggression pact between the four nations of Gamidustri, each nation's capital comes under attack from armed forces flying the flag of another nation. Finger pointing ensues, and eventually devolves into a four-way brawl between the four CPUs, leading to the annihilation of the city hosting the signing ceremony. Unable to reconcile, this conflict further devolved into all-out war.
Fan Fic / Overheat
Gamindustri is ravaged by the all-out war between Lastation, Planeptune, Leanbox and Lowee. Open animosity between nations, research into deadly and outlawed weapons, each of the four super powers has to always take it still one step further to triumph over their enemies. In a world like that, love is a rare thing to find and even rarer between enemies. And yet it exists.
—Summary of Overheat