alt Hacker News> Project Gemini
I have a theory that the idea you'd call your project "Project X" comes from TV shows.
We work with project codenames and we don't call anything Project X. We just call it X. It feels like adding the word "Project" is something a screenwriter would do to make the dialogue clearer.
I would say that it comes from the military, where projects are given codenames that try hard to be opaque random monikers, and spill no beans about the nature of the project. The Manhattan Project predates mass TV, and most of it did not happen on Manhattan.