Release notes here.
This one is a HUGE and exciting change to the base game: the endgame has been completely overhauled for AI War. Previously, the home planets for the AI were always very similar to one another, and often they were something of a grind.
The chief problem was that things were too centralized on a single unit on those planets: the AI home command stations. You had to destroy those, and that was really the only goal; therefore, that was super hard if you didn't have enough firepower, or really easy if you did.
Now the emphasis is on a distributed network of specialized, much stronger guard posts, as well as a much weaker central home command station. However, the central home command station can't be touched until all the new AI Core Guard Posts have been destroyed, which means that there are many goals on the planet before you actually get to the final goal of killing the command station itself.
There are 9 new types of these specialized guard posts, with various abilities. Rather than enumerate those here, we'll let you discover those in-game. Some are more rare than others, and your seeding is different every time, which makes each AI home planet quite unique now. There is also room for expansion over time with more specialized guard posts in addition to the first 9.
The overall net effect is that you can take on the home planet a chunk-at-a-time now, and you can successfully destroy a chunk and then come back much later without having lost any progress. This is a big improvement over the old system, where you had to build up overwhelming force and win all in one big push; again, that tended to be either too hard or too easy (usually too hard).
Going along with the above, there is now quite a bit of strategy and puzzle-style challenge to figuring out the best attack pattern and order for actually clearing the guard posts on the AI home planets. Some of the guard posts are likely to support one another, and so your success depends on your ability to make and execute plans here. The goal is to make the endgame as strategic as the early and middle game, rather than it always devolving into a grind or a cakewalk right at the end.
Lastly, the AI home planets previously had really inflated ship caps, in that even if you destroyed guard posts it was impossible to neuter the AI home planets at all. This is no longer the case, and the AI home planets can now have their effective ship caps whittled down over time. This way the battles remain epic, but not laggy or grindy, hopefully. More tweaks may be needed to this over time, too.
All of the above DOES affect all existing savegames loaded in the new version. Enjoy!