PCGamesN reports that the DLC for Mutant Year Zero: Road to Eden will arrive later this year.
Information on the DLC is pretty sparse at the moment, but we do at least have a release date - you can expect to head back down the Road to Eden this summer, on June 25. Presumably, the DLC will be an extension of the story from the base game, but how exactly that'll be approached isn't clear just yet.
