Let's Play Armored Core: Large Text Dump
Since I've basically completely skipped the story so far, here are some emails from R to explain the various factions that make up the future world of Armored Core.
Let's start with Murakumo Millennium and Chrome themselves:
From: R
Chrome and Murakumo
Zam City was one of the very first cities built in the underground city development program, so redevelopment is proceeding in various areas of the city.