Crimson Eternal: An Immortal Death Mage LitRPG Apocalypse

Death is an inevitability for all except Aria. Something she knows all too well. In a world locked in war, with the majority of its continents already wiped out before the signing of the Great Treaty banning strategic level weaponry and magic, Aria Crimson finds herself lost. Treated as a weapon by the military since she was young, she has almost forgotten what it was like to not be at war. But when a strange looking screen similar to those of the newly created devices known as computers appears in front of every last person on the planet, things change. Every human on the planet is given a class and a way to level their class. Given a new way to power outside of just their natural-born abilities. But along with the power comes the invaders. Humans from another world declaring war on their world, trying to take it for their own. Now, after ten years of fighting, Aria finally has a way out of the war. One that involves even more fighting. How will the world react to the changes, to the invaders, and to the power granted to them? And how will the only True Immortal in the universe, one dubbed by the System as Death, one of the Four Horsemen of the Apocalypse despite the irony, choose to proceed? A protagonist who travels across a lot of worlds in their immortal life, slowly growing stronger throughout it with lots of time skips.