As expected, this one is mostly just to fix some bugs in the prior version. It also improves sniper turrets, spider turrets, and how firepower ratings are calculated.
This is a standard update that you can download through the
in-game updater itself, if you already have 4.000 or later. When you
launch the game, you'll see the notice of the update having been found
if you're connected to the Internet at the time. If you don't have 4.000 or later, you can download that here.