The first DLC pack for open world zombie game State of Decay is planned for release "by the end of October".
Undead Labs executive producer Jeff Strain announced the game's first add-on, titled 'Breakdown', in a post on the studio's website. He said it has been delivered to Microsoft for pre-certification testing.
"Through next week the QA teams will be playing Breakdown, logging any issues they find, and sending feedback to the development team. We'll spend our (probably quite long) days reviewing, prioritizing, and squashing bugs, and incorporating the design feedback from the QA teams, members of our publishing team at Microsoft, and of course our own developers here at the Lab.
"The plan is to have all that wrapped up and submit formally to certification testing at the end of next week. But, assuming no catastrophes, we plan on getting Breakdown into your hands by the end of October."
Breakdown designer Geoffrey Card said in another blog post that the DLC has been designed to significantly boost the game's difficulty level.
"One thing we know our community has been looking for is a new challenge. You've spent all this time mastering the game, and you want somewhere to go to truly test your skills. Breakdown is designed to bring on that challenge. As you progress through each iteration of the game, the scenario gets tougher and tougher. The game is daring you to try and survive, and is ramping up the difficulty each time you do.
"I've made it my goal to create a version of the game that gets so hard by the end, I can barely play it, and then let you folks show me how it's done. Are you ready?"
Last week, Undead Labs said that it had sold one million copies of the game, which launched on Xbox Live in June. State of Decay released on Steam Early Access on September 20.