Gate

A rift opened over North America's east coast, shattering the sky and heralding the demonic invasion. Humanity has been pushed back into cities as gates into demon strongholds [dungeons] sporadically appear throughout the world. The only thing stopping the complete annihilation of the human race are the guilds of Heroes who delve these gates for glory, resources, and duty. Civilization sits on a knife's edge as humanity is pressed into mandatory training for dungeon delving after high school. Join our heroes as they start their freshman year of college and find themselves pushed into the Elite class of gate delving.