NIKKE: outsiders

In the year 2089, mechanical aliens called raptures has invaded earth with their high technology and high numbers, the military isn't enough to stop them, forcing all humans to live underground and away from those Invaders, the humans build a new civilization called ark but they knows that this is not the way to live because they know the surface is their true home and now they want to fight back, but they know they are current weapons are not enough to even scratch those so-called raptures so they start to produce a new type of weapons called nikke, they basically replace human military because they are far more effective against those raptures. In the same time another group of human that still remain on the surface also created their own civilization called eden and manufactured their own nikkes to fight against those raptures. And do you think that's all? In this timeline instead of just having these two factions, there is also one more that is beyond these two factions location, deep under the ocean another group of civilization decide to stay isolated to prevent being attacked by those raptures for quite some time until recently they is out of the ocean and head to the lands to fight those raptors with their own nikkes