This video was made entirely by members of the Team Fortress 2 community, and supported by Valve as an official update with cosmetic items, a duck-based in-game event, and a new melee weapon designed to look like a train crossing guard.
The map was originally intended to be released alongside the initial update, but Valve deemed it "too confusing for new players" and the map was not released until the Gun mettle update.
When the map was open to testing, certain props and models were removed in place of ERROR meshes due to them being related to the then unreleased SFM.