Grey Goo features hotkey controls for unit and structure building, but unlike the hotkeys used in StarCraft and many other RTS games, these are based on the WASD keys, with tiered menus that each use the same set of keys.
The game is set to be focused on Macro gameplay instead of Micro management. Just like previous RTSes from both Petroglyph's and C&C's past, harvester units will be automated and there won't be any dedicated builder units. Instead, base building will be based around a hub system where new hubs of varying sizes can be placed where the player wishes and add-ons can be built onto them to determine their purpose.
Grey Goo will have both single and multiplayer modes. There will be a traditional 15-mission campaign with sets of missions for all three factions. It has already been confirmed that there will be an offline skirmish mode with an AI that is supposedly based off of Defense Advanced Research Projects Agency (DARPA) AI theories.
Similar to their previous RTS title, Universe at War: Earth Assault, Grey Goo relies on a 3rd party system for its multiplayer setup. However, in Grey Goo's case it will be Steamworks instead of Games for Windows Live (For which Universe at War was actually one of the first titles).
Grey Goo is set on the planet Ecosystem Nine. On this planet, the three factions of the game end up meeting once again.
By the time of Grey Goo's events, Humanity has found expansion through the Galaxy to have become too costly- and have internalized themselves to look to their own preservation. They saw themselves as the strongest force in the galaxy, but wished to end their internal wars. So much of Humanity's infrastructure for war has been disbanded, and major decision making has been relegated to AIs to lessen tensions. Now having only an academic-basis of knowledge for warfare rather than actual experience, the Human expedition to Ecosystem Nine must look into this knowledge to defend themselves when they investigate an old signal emanating from the planet.
In terms of play-style, the Humans on a basic level innately favor defense and turtling. They have the most versatile walls in the game, since their units can move and shoot through them freely- and they can also relocate their turrets along their conduit lines as necessary. The Humans do have the most constricted bases of the factions though, since all of their structures must be connected to conduit lines to function. The Humans are not without offensive options though. For instance, they can tech up to Teleporter structures that can send groups of 5 units to anywhere they have LOS on the map.
A race of four-armed technologically inferior aliens who have previously almost faced extinction. Their last ship to escape the devastation just barely made its way to Ecosystem Nine. Since then, the Beta have simply been trying to rebuild - and only remember their ancient assailants as 'the silent ones.' Having re-developed almost to the point of resuming space travel, the Beta's prototyping and experiments are suddenly disturbed by the almost simultaneous arrival of the Humans and Goo on Ecosystem Nine. Some in the Beta's command structure are convinced that these are 'the silent ones' with new weapons, but others mention that none of the new assailants match the old descriptions.
Gameplay-wise, the Beta are arguably the most traditional and balanced faction in the game- not as fast or aggressive as the goo,but not as innate to turtling as the Humans. They are capable of building their hub structures anywhere they have line of sight, allowing for highly traditional base building and easily-setup proxy bases. Defensively, the Beta have solid walls that cannot be passed or shot through by any side- but can be garrisoned by some of their unit types to act as towers. In fact, one of their unit types, the Guardian, MUST garrison a wall to attack at all. Offensively, their capabilities of building anywhere they have LOS and some upgrades- such as stalkers upgraded with stealth and sniper equipment- give them a surprising number of options for varied attack vectors.
The titular faction of the game, the Goo were originally a force of nanomachines created by Humanity purely for exploration. The Grey Goo was thus responsible for paving Humanity's path through much of the solar system and galaxy, until they determined that such expansion was becoming too costly. At that point, Humanity haphazardly disbanded the Goo in deep space. A century has passed since then, and the Grey Goo has re-emerged as a seemingly re-purposed horde of now self-replicating nanomachines carving a path of destruction back the way they came. The origin of the faction is thus heavily based off of the Science Fiction theory of the same name.
The Grey Goo faction is completely based around the Mother Goos. These Mother Goos are capable of moving from one resource point to another as they please in order to grow in health and mass. They can keep their position in constant flux as they split off new Goos of varying sizes that can then form into dedicated combat units. The result is a completely mobile faction with no set base locations or structures whatsoever. The Mother Goos are the faction's resource harvesters, research centers, and unit producers all in one.
The nature of the Goo's unit production also allows it to be the most reactionary of the factions, as they can delay morphing the goos into dedicated combat units until combat is joined- at which point a quick thinking player can easily morph them mid-combat to directly counter whatever the opponent has on hand. The goos are also outstanding at ambushes, since the unformed goos can travel over cliffs and elevation without limit- allowing them to break LOS with enemies easily so long as they have no air support. This is made even better by the fact that the unformed goos can serve as vicious melee combatants that eat whatever they can catch. The mobility of the unformed goos arguably partially makes up for the faction's complete lack of air units.