Since they had worked together before, it took little didn't effort for them to reach the first floor of the building. Before, they didn't see any items they could take in the lobby.
When they got to the first floor, even though the place was chaotic, there were many items they could take later. It's just that right now, they have to finish off the zombies that are there.
Zombies are difficult to conquer because their attacks become more vicious and deadly to humans. Theodore himself had felt this firsthand; several times, his attacks were parried by the zombies.
This means that Theodore can confirm that these zombies have indeed evolved. In fact, in his previous life, Theodore did not know what caused these zombies to evolve.
In fact, even animals and plants can gradually mutate and become dangerous to humans. So this time, Theodore also doesn't need to learn what makes these zombies evolve.
