Mafia Wars (Zynga, 2008-2016) was a social strategy game, not an RPG. No character progression, skill trees, narrative choices, or exploration.
Bottom line: Mafia Wars was a viral social strategy loop wearing RPG clothing. For actual roleplaying in a mafia setting, look to tabletop (Vampire: The Masquerade, Blades in the Dark) or narrative browser games (Fallen London).