Killing Floor 2 has released on Steam Early Access. If you enjoyed the first Killing Floor game, you'll certainly want to look into KF2. From the developers at Tripwire Interactive:
They said there is a chance for multiple stat and perk progress wipes during early access. So if you don't want to have to repeat your progress you may want to wait until it is in a released state.“This is the Steam Early Access for Killing Floor 2. The game is what we consider a "polished beta" and is ready for you to play, just with a reduced set of content, so that we can get player feedback on the balance and gameplay. That feedback will help us get the game to be the best it can be, as we add the rest of the content, piece by piece."
If you could care less - grab it and start killing!