Doomsday: I Just Want to Simply Defeat Monsters and Level Up

No, why did the world turn into chaos just when I went downstairs? Zombies? Monster? Monster? Mutant creature? Crusu? Decline politely, don't disturb me, I'm sorry, I'm not at home. I just want to live. What, defeat monsters to gain experience, BOSS will drop equipment? I wouldn't be sleepy if you said this. I have a showdown, reported by a ten-year MMORPG fan.