Apocalypse: I Can Travel Between Two Worlds

After transmigrating into an ice age apocalypse, Lin Mu obtained a ring that let him travel back and forth between two worlds. Then the entire apocalypse was turned upside down! From gas-cylinder cannons to tanks, then attack helicopters and nuclear bombs! The weapons Lin Mu brought out one after another made the entire otherworld tremble. With the ring, Lin Mu gradually rose to power amid the crisis, rejecting every attempt to guilt-trip him and eliminating each potential threat... [PS: No self-sacrificing saint, harem story. If that's not your thing, don't read.]