The System alters the nature of the world and seeds Zombie Qi across the planet. Those that have the potential to become immortals have their cultivation path unlocked, those that do not become an abomination as the Zombie Qi alters their mind and body forever.
The earth becomes hell and the only escape is to achieve immortal ascension.
The story follows three brothers, Elijah, Moses and Abraham. All in their 90s they were career soldiers. Fighting in WWII and Vietnam before waiting for death in the hospital in their old age.
When the System comes they have another chance at life, a chance to be young and a chance to ascend.
This is Zombie Xianxia.