The base game, meanwhile, has already sold over 5 million units since launching on PS4, Xbox One and PC in January, a milestone which Techland describes as a "tremendous success".
"To be honest, I think even we are a little surprised by the scope of our success," producer Tymon Smektala told VideoGamer.com at last week's Gamescom. "We knew that we'd made a good game. If you are a gamer, even if you make games you are still a gamer, so we know the game is good when you feel that rush when you play.
"So we knew that Dying Light is a good game, we know it's going to be successful, but that successful? We are in the 10 best-selling games in the US right now for the first half of the year, so tremendous success. More than 5 million copies sold."