Rise of Nations 2 (lost sequel to real-time strategy game; date unknown)
From The Lost Media Wiki
Rise of Nations is a 2003 real-time strategy game developed by Big Huge Games and published by Microsoft Game Studios. The game was critically acclaimed and is considered one of the best real-time strategy games ever made. An expansion Rise of Nations: Thrones and Patriots, was released in 2004, and a spin-off, Rise of Legends was released in 2006.
However, not many people know that there was a proposed sequel to the game, only known as Rise of Nations 2. Little is known about this lost game, as the only proof of its existence is on a Steam discussions post where a now-defunct user linked three screenshots presumed to belong to the lost game.