The new 20-minute short with Dr. Rosalene and Dr. Watts should now be updated into your Steam folder. c: It's currently Windows-only, but the Mac version should be incoming soon, with the Linux version sometimes this week.
Post & info here:
http://freebirdgames.com/2015/02/18/sigmund-minisode-2-released/
To play it, get the free DLC, and then launch the game manually from the To the Moon \ Minisodes folder in your Steam directory.
Hope you enjoy it!