[This fic has a loooooooooooooooot of math]

This is a story about Tod, a dungeon core who's tired of the dungeon life, and decided to do something more slice-of-lifey. So, the gods allowed him to take a vacation and create a subway network as a 'dungeon'. He also gets a human body to experience life as a commuter, where he can eavesdrop on commuters, spy on their daily lives, eventually, also gets an ability to see a status summary of his commuter's lives, how much money they make, where they live, what they do and all that. 

All, so that Tod can build a rail and transit network as a dungeon core that is bigger than everything the world has ever known.