Dungeon Battle Royale: Maou ni Natta node Sekai Touitsu wo Mezashimasu

One day everyone on earth suddenly receives a mysterious survey email. The mail states that the world salvation project has begun and that everyone will be divided into LAW, CHAOS and NEUTRAL. Shion Kurosaki, a loner freshman in university, was sorted into CHAOS. Which means that in the new world he is to be a Demon Lord who needs to prepare his dungeon, fill it with monsters and fend off the attacks from the LAW heroes. A dungeon building adventure begins!

(Source: MangaPlaza)