[There is no savior who breezes through with an overpowered advantage here, only ordinary people struggling through hordes of zombies and growing through blood and tears. If you want a protagonist who plans for everything, never puts a foot wrong, and always comes out on top, this may not be for you.]
Zhang An dies in a zombie horde, then wakes in the darkness.
A voice tells him: Survive for three years, and you'll be granted a new life.
The first time, his companions lock him outside, and his body is torn apart.
The second time, he makes the same mistake.
The third time, he changes one line of dialogue and lives a few hours longer, but personally cuts off his companion's leg.
The fourth time, he returns with all his memories, only to discover that every struggle he makes is feeding data into a cold “observation report.”
Being bitten apart by zombies isn't the most terrifying thing. The truly terrifying part is realizing that your pain, your choices, and even your death are nothing but a “soul sample” being weighed in the eyes of a god.
And through countless cycles, he must prove that humanity deserves this apocalypse.