The Manchurian Gold that was in the crates, causing all the people to go crazy, is it based on a real thing?
Theres no known bio weapon called Manchurian Gold, so this much seems made up. It was manufactured at the fake water purification plant in Manchuria, China, which is where it gets part of the name. The gold part being the color.
The ship from the game is based on the SS Ourang Medan, which has a pretty interesting story around it as being a ghost ship. There were some soldiers who were meant to have died from a chemical weapon on board that turned into a gas when sea water flooded a portion of the ship. So that’s where the idea likely came from.
So while Manchurian Gold is not a real thing that we know of, the story is loosely linked to an urban legend around the actual real life ship.