Somebody got creative and modified Death Note Mafia into The World Ends With You Mafia. The first three games were a lot of fun and the last one nearly gave us all heart attacks~ People screaming at their computers and such lol.
Basically there's a large group of people and one or two of them are Reapers. You have to kill them before they kill you, and depending on your role you might have special abilities. The only problem is, you can't trust anyone... so you have to use all of your investigative skills to figure out who is killing the other players during the night phase, and then convince people to trust you, because players are erased via voting.
It's a chat room game, so if you're familiar with the characters and would like to play, I'll send you the link.