Black Ops II is made by Trayarch and Ghosts is made by Infinity Ward. The new game, Advanced Warfare, is being made by Sledgehammer Games, who assisted Infinity Ward in making Modern Warfare 3 since a majority of Infinity Ward's team left the studio after Modern Warfare 2. Those people who left then formed Respawn Entertainment, who made Titanfall under the publisher EA vs Activision.
English
-
Why did they leave?
-
Because Activision fired them and practically took over CoD themselves, so that they could milk it for all eternity
-
There was a lawsuit filed on the heads of Infinity Ward, Jason West and Vince Zampella, after they delayed some MW2 DLC to stop its release from conflicting with the release of Battlefield: Bad Company 2 or something like that. As a result of the lawsuit, Jason and Vince were fired, but then a majority of the team quit to join them at the new studio, Respawn.