Grey Goo is a real-time strategy game set in the distant future on a planet called Ecosystem 9. The Beta have settled on Ecosystem 9 in a final attempt to save their civilization which was nearly exterminated in events set before the story of the game. After enjoying peace at first, their new home is now threatened by mysterious exploration robots known as Goo as well as a Human research vessel.
The three races each have their own strengths and weaknesses as well as their own set of units and buildings. Raw materials have to be gathered in the form of crystals. They are needed to construct a base so that you can recruit troops. For example the Humans' strength lies in defense and the Goo’s in mobility. The game offers a single-player story mode and a multiplayer mode for up to four players local or online.
The phrase "grey goo" has been used to describe out-of-control von Neumann nanomachines (microscopic self-replicating robots) since being coined by author Eric Drexler in his 1986 book Engines of Creation.