The story of the Armored Core series has been rebooted at least three times in 25 years, but the premise has never varied much from some core themes. You are a mercenary. The world is run by quarreling mega corporations. The Earth has been ravaged, or is on the brink of a ravaging. Everything sucks except the mechs, which are hella cool.
There are some actual narrative details to be gleaned here—a squad of pilots with numbers rather than names (617, 619) die while assaulting an yono app enormous cannon emplacement. "Well, at least you're helping me clear my inventory," says an unnamed voice. Another pilot, 621, is laid out on a table, all kinds of nasty sci-fi medical equipment surrounding them. A clone? A test subject? Whoever they are, that's probably who we are, as the end of the trailer implies 621 will be the pilot we control in AC6.
I'm giving you permission to watch and re-watch the above trailer and not care about any of that, because in between those scraps of dialogue are immaculately animated sequences of mechs firing missiles and gatling guns, being melted and blasted to bits, and dodging to-and-fro with lateral jets. The somber music that plays as yono sbi they become slag says that I should be sad, but I don't know how you can watch this footage and be anything but giddy. If mechs get much cooler than this, I don't know if I can take it.