It is a gameplay mod(ification) of the game 0 A.D. 0 A.D is an open source Real-Time Strategy game similar to Age of Empires series. This mod acts as a proposal to include the Auto-Queue feature into the game officially.
At the time this mod was made, 0 A.D, similar to its inspiration Age of Empires, has manual queuing system in unit production. It means that you have to explicitly train units repeatedly to produce multiple units.
This mod proposes an auto-queue button. It means that with the auto-queue button toggled on, once you select the units it will be produced infinitely as long as the resources needed are available. This eliminates repeated, micromanagement tasks and enable player to focus on strategy. This feature has also been implemented in Age of Empires successors like Age of Mythology and Rise of Nations. You can check the discussion about this proposal in Wildfire Games forum.
I'm proud to say that my auto-queue proposal is finally accepted and it has been a part of 0 A.D release since Alpha 25, and it has been improved significantly by the community since then. You can see the initial pull request in this Differential. This repository is just archive.