Heya folks. (Sorry for reviving the thread)
I wanted to get 'Killing Floor 2' working with this addon and since I seen the 'Unmaintained' tag, I figured, I would chance my arm at it. Loe and behold, I got it working.
I have uploaded the code which should be put into library/GameServers/GameQ/gameq/protocols
Also, do not forget to update the Servers.php file (Located in /library/GameServers/Model/Server.php ) (I placed this under 'Killing Floor' but you can stick it anywhere!!)
"killingfloor2" => "Killing Floor 2",
I am not a PHP developer...I just sorta copy and pasted things in and see what worked. Easy enough to follow for each game.
While this is one way to do that, you could also just use the built in "source server" option for the server type. It works with all servers that use the source query protocol.
Not sure why there is an unmaintained tag since I still provide support and bug fixes.