Amalgamated Corporation is an international company, which arguably caused the apocalypse, as stated by Marion G Harmon.
Amalgamated is portrayed as a very wealthy corporation. Amalgamated is the proud producer of the in-game item, the Surviviotron VI, a walkie talkie players can use to talk to each other, along with other unseen products, like "AC Sportsdrinks", an innocent sounding sport drink, and "AC Happytabs", which seem to be some form of legalized drug, presumably a hallucinogenic or psychedelic substance, considering what Harmon said about the tabs.
Amalgamated also owned several infrastructure locations around Orca Island, such as the Amalgamated Airfield, and Orca Dam. This falls in line with Amalgamated being an international corporation, controlling power, transportation, and employment. Amalgamated also created several military bunkers on Orca Island, which are supposedly designed to withstand nuclear blasts and fallout.
Amalgamated also was allegedly a weapons producer, and supplies multiple nations with "AC Battlegear" and nuclear weapons, along with attempting to produce a "vaccine" for radiation sickness. The vaccine, appears to be in pill form, as depicted by Graffiti found around the map. It is also advised, by said graffiti and by Marion Harmon, not to take the vaccine, as it supposedly is the cause of the Mutation problem we see throughout the game.
ACHCR is a supposed refugee agency created by Amalgamated Corporation. The letters ACHCR are usually to the right of a Amalgamated logo, and both are above the catchphrase "The AC Refugee Agency". This arrangement of AC paraphernalia is found at ACHCR sites on various pieces of equipment. ACHCR presumably stands for "Amalgamated Corporation Hayward valley Center for Refugees". The Refugee Center, as depicted by the supposed acronym, is located in Hayward Valley, as said by supposed acronym.
ACHCR equipment can be found in many locations throughout the game, it can be found in every town or city, as well as at other points of interest, such as the Airfield or the Dam, and several supposed military checkpoints along highways.
ACHCR is a parody of the United Nation's UNHCR, The UN Refugee Agency.