The year is 2084. Most civilzations have long fallen, but Rust still lives. A group of Rustaceans in a Shell (a Rustism church) pray to Lord Ferris about how to save the barren world. The chief Rustist bishop (the Headcrab) announces, “Our great Lord Ferris has told us that we need to conquer all the lands in order to make Rust the only language, spoken as well as written.” This is how the Great Oxygenation Crusade began.