Why is it still not out? It was first revealed and playable during NYCC 2014, its been about 5 months.
Because we wanted to do a bunch of refinement to it. This isn't Tripwire slinging out some cheap-sh*t mobile game. Its a Killing Floor game, so we want it to be good! Besides, all the different platforms start to drive you all nuts... figuring out good control schemes, performance, etc.
iOS - tablets and, ideally, phones.
Windows - aimed at tablets, but obviously will also play on most windows devices.
Android - (long list) - standard Android build for general tablets, graphically-enhanced version for the Shield tablet and portable, version for the Amazon Fire TV (as seen on Amazon's Twitch feed last week from about 1:44 on this feed:
http://www.twitch.tv/firetvgames/b/632721368). And, ideally, phones. And the new Nvidia Android TV console.
Main issue with phones is figuring out the best zoom/view, on the small form-factor. It already runs on my 3-year-old Samsung Galazy S3. Just a small screen!