A Steam Community Group Announcement has an update from KillHouse Games on Door Kickers, including word that the top-down strategy game will soon be available next month as a retail release in Germany. There's also word to expect first details on Door Kickers 2 on January 17th (thanks Gamer's Hell). Here's what they say about plans to unveil the sequel:

As 2015 has come to an end, it’s time to talk about the future, and the future is Door Kickers 2 … and more.
DK2 brings the step to 3D: environments, characters – but keeps the clear and easy-to-use top down perspective and hardcore, unforgiving action. It keeps the real life action but moves it to a new and exciting setting. And it changes … everything.

Oh, are we being a little vague? Yes, we are.
On Sunday, January the 17th of 2016 you will know more. In case you wonder, that’s exactly 3 years after we let the first news out on Door Kickers.