Welcome to the City of Rules [Infinite]

The author's completed novel of the same genre, "The Doomsday Cruise [Infinite]," is available in the author's works. Every world has its own rules. Anyone who breaks them will be punished. [Open your eyes and relax. You'll soon find that this place isn't all that different from your world. Perhaps our punishment for rulebreakers is a little harsh, but if you're a good citizen, you have nothing to worry about.] [Come along. Seek out the rules and explore the city. As you endure countless trials in different instances, you will fulfill the deepest desires of your heart.] [Now, let's confirm the new status you're about to receive. Assessment begins!] "You are the kind of person who smashes every pot in Dragon Quest." "You are the kind of person who completes the entire Pokédex in Pokemon." "You are the kind of person who reveals every inch of the map in Diablo, leaving not a wisp of fog unexplored." "You are the kind of person who braves hidden ambushes in The Legend of Sword and Fairy and explores every branch of every maze." "You are the kind of person who collects every Riddler trophy in Batman: Arkham Knight." "To sum up, your talent is... Gaming Completionist Syndrome." [Assessment complete. One last thing: Welcome to Rule City.] [Whether you leave alive or become one of us is entirely up to you.] As Mu Ai watched the scenery before her gradually change and the Rulebook that had appeared in her hand for no apparent reason, she muttered under her breath, "After all that talking, I thought I might get an [Adventurer] achievement... That's it? That's it? What a lousy place. It's doomed!" As for what to do next, Mu Ai figured that since she was already here, she might as well collect all the side quests and items in the instances. Theme: Persevere through hardship and stay optimistic