Call of Duty: Black Ops 4 is a multiplayer first-person shooter developed by Treyarch and published by Activision. It was released worldwide on October 12, 2018, for Microsoft Windows, PlayStation 4 and Xbox One. It is a sequel to the 2015 game Call of Duty: Black Ops III and is the fifth entry in the Black Ops subseries as well as the 15th main installment in the Call of Duty series overall. Black Ops 4 is the first Call of Duty title without a traditional single-player campaign mode. Instead, it features the Solo Missions mode, which focuses on the backstories of the game's multiplayer characters, known as "Specialists". The missions take place between Black Ops II and III chronologically. Some of the Specialists also carried over from Black Ops III. The multiplayer mode is the first in the series to not feature automatic health regeneration and introduces both predictive recoil and a new ballistics system. The game includes three Zombies map on release day, four if a special edition of the game, or the Black Ops Pass, is purchased. The locations of the maps include the RMS Titanic, an arena in Ancient Rome, and Alcatraz Federal Penitentiary. The game also introduces a battle royale mode called Blackout, which features up to 100 players in each match. Many characters from this and other Black Ops titles can be used as the player's character model in this mode.