This one adds two new bonus ship types: the Zenith Reprocessor, and the much-anticipated Zenith Siege Engine. The latter has to stay immobile for 15 seconds before firing, but it hits like a truck once it does. A truck loaded with plasma torpedoes, that is.
Another long-requested change, from the top of the mantis voting page: the Clusters map type. In a way, it organizes the galaxy into 2 to 6 smaller units, each of which only has a few connections to other clusters.
The name of this release, however, comes from the new AI Type: the Fortress King. Fortress Baron not enough for you? Well, here you go. There's a small mercy included: AI planets bordering your homeworld (unless they're somehow AI homeworlds) will only have the normal command stations. All the other Fortress King planets will have mammoth modular fortresses (that eat bombers for breakfast) that function as command stations. Each one rolls its modular armament separately from a set of templates, so it adds a bit of variety to how your fleet will be (repeatedly) eaten.
Several other fixes and changes, as usual. I'd intended to get the next nebula scenario into this release but I'm probably going to need to divert to helping Chris with a particular subsystem of Shattered Haven, so I wanted to get this into player hands now rather than later :)
Update: 5.071 hotfix is out to fix several bugs with the Fortress King AI type. Also fixed some other issues and packed in some further changes to CPAs and some funny business involving barracks.
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.