A new leak suggests Call of Duty: WW2 developer Sledgehammer Games was once working on a battle royale mode for the 2017 shooter. While Call of Duty: WW2 could have been the first entry in the franchise to implement such a mode, it was Call of Duty: Black Ops 4 that would make the leap into the battle royale genre, followed by the monumentally successfully Call of Duty: Warzone, which launched in March 2020.