Crime Game - Houritsu no Nai Sekai is a Manga/Manhwa/Manhua in english language, GORE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Amagoe Homura, a high school student you can find anywhere, finds himself in a devastated version of Shibuya. A mysterious figure calling himself "Unknown" tells everyone that they can commit any crime in this world, and forces them to participate in a death game where they compete on who can commit the most severe crime...!