Wait, is this about that novel sometimes listed as 'Overlord Zombie' on Webnovel? Or the translated ones on aggregator sites? I think there are a few different stories with that mix of terms, but the most likely one is that the official title is 'Survival Story of a Tyrant in a Zombie Apocalypse'. I read it on KakaoPage. The main plot follows this protagonist who gets regressed back to the start of a zombie outbreak, but he used to be this morally bankrupt, power-hungry gangster-type figure in his past life—not your typical heroic reborn guy. He's got the memories of his previous timeline where he was basically a monster, and he's trying to navigate the early chaos with that ruthless mindset intact. It's less about saving humanity and more about securing his own survival and building a fiefdom from the ashes, using his foreknowledge and zero qualms about manipulating or eliminating others. The zombies are a constant threat, but the real tension often comes from conflicts with other survivor groups and the internal struggle of whether he'll become the same 'overlord' tyrant again or if something might change him. The power system involves evolving zombies and some humans developing abilities, which he tries to exploit.
I dropped it around chapter 80 because the protagonist's sheer amorality started to wear on me—it's a very specific taste. But if you're into grimdark, pragmatic survival stories where the main character is genuinely not a good person, it's definitely a unique take on the genre. The writing is pretty blunt about the violence and the moral compromises, which some readers might find refreshing compared to more sanitized apocalypse tales.