Call of Duty: Black Ops is … The Vietnam War was a Cold War -era conflict between South Vietnam and it's anti-communist allies against North Vietnam and its pro-communist allies. Call of Duty: Vietnam (internally titled Fog of War) is a cancelled installment of the Call of Duty series that was under development by Sledgehammer Games. It was stated to be taking place in the 1960s and 1970s, in Cambodia, Vietnam and Laos. Call of Duty: Black Ops was deemed “ tacky ” by some Vietnam War veterans.