This one completely re-imagines Astro Trains. The trains had really fallen out of player favor a while ago, so we shuffled them off to be an AI Plot until we could think of a more interesting approach. That day has come.
The release notes have the details, but some highlights:
* Astro Trains are now a variable-intensity plot like Hybrids. So 0/10 is "off", 4/10 is "normal", 1/10 is "trivial", and 10/10 is "game-dominating".
* Trains will never be a direct threat in and of themselves (except the nuke train, but that only shows up if you crank the plot intensity all the way up to 10, and then only very rarely), but the support effects the provide (generally just on their current planet) will range from annoying to devastating. And since the trains travel in bigger groups on higher intensities, it can really stack up.
* The really nasty trains are much less invincible than the others, but even those will be hard to kill. You can influence where the trains go by killing off train stations.
* The cargo trains are totally harmless in and of themselves, but their deliveries make progress toward a construction project for the AI (it'll alert you as that gets past 50%).
In summary, you probably won't want to turn these on unless you want more pain in your game, but since that's a significant portion of our audience here you go :) It's also good for folks who want to see how well their impenetrable defenses can hold up under extreme conditions, particularly on the higher intensities.
Trains aside, this patch also addresses a longstanding player desire for an easier way to search for ships (player and AI): there are now two "custom" galaxy display modes that let you pick the target type from a dropdown. Further, while this dropdown is expanded you can type part of the name of what you want to search for and it will narrow the dropdown down to items that contain the text. This incremental-search approach is now also used by the select-target dropdown on the reference tab of the stats window.
There are also some important bugfixes, and some balance changes.
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.