A Total War Saga: Troy was downloaded by 7.5 million people during its giveaway last week.
Creative Assembly's strategy title was available for free on the Epic Games Store for 24 hours from its August 13 launch date.
It was downloaded by 7.5 million unique users during that time period, the UK studio said, a level of interest it "couldn't have predicted."
A statement from chief product officer Rob Bartholomew suggested that the goal of the promotion was to bring a large and diverse group of players into the Total War series.