Project Solaris is a moon base controlled by the USSR and the Blisk alien race, both of whom are allied together. However, the Blisk treat the Russian workers badly and control them as mere slaves for their nuclear mining. Furthermore, the Blisk manipulate them into not knowing that Project Solaris' real intention - Developing a Blisk super weapon on the northern half of the moon in a large dome, which would launch spores onto Earth, turning it into a water-lodged haven for the Blisk, having lost control of Mars. This is also shown by the project's leader, Premier Milenkov, leaving the Russian people on their own, so Milenkov and the Blisk could further contribute to the project.
Cosmonaut Base: The Cosmonaut Base is situated in the center of Solaris, and is the home of the cosmonauts, housing four connected biodomes (a park-like biodome, City Dome, garden biodome, and one with seemingly no purpose).
City Dome: City Dome was the largest of the four domes in the Cosmonaut Base, and contained the nine houses that the cosmonauts slept in. Unlike the other biodomes in Solaris, City Dome's shell could be penetrated without being destroyed by Furon weaponry.
Mining Site: Sitting in the northwest, the Mining Area was a complex of tunnels and a small base outside where the cosmonauts mined uranium (via Ursa Miners). The mine was attacked twice by Furons: once to destroy the Ursa Miners there, and the second time it was being used as a Blisk stronghold in till it was cleared out.
Solar Array: An area in the northwest, south of the Mining Area, where a mass of solar panels powering Solaris was located. Located outside of Cosmonaut Valley.
Lower Solar Array: An area in Cosmonaut Valley west of the Solar Array.
Radar Dome: A large dome and the surrounding buildings used as the laser tracking system for the Global Sporifying Weapon (GSW) the Blisk planned on using. It had an energy door for a shield, but Crypto shut it down.
Tennis Court: A mysterious biodome outside of Cosmonaut Valley, east of Radar Dome. The biodome only contains a tennis court, and no cosmonauts stand nearby.
Communications Zone: An area in the south, used for communications and shuttle landings. The Eagle landed here.
The Northern Tunnel: A tunnel through the Valley Ridge, going from the Cosmonaut Base to Blisk Road.
The Southern Tunnel: A tunnel through the Valley Ridge, going from the Communications Zone to Blisk Road.
Blisk Road: A road to the west of Valley Ridge and east of the Blisk Base.
Blisk Base: The main Blisk hive, situated in a lake of poisonous goo in eastern Solaris. The base was divided into two circular parts, connected by a tunnel, and was destroyed in an attack on it.
Cosmonaut Valley: A valley making a circular dip in most of Solaris.
Valley Ridge: The slopes of Cosmonaut Valley. Many small biodomes are located on its steppes.
Unknown area: located between the main dome area and the Blisk Area (south west of the Mining area landing zone) is a short tunnel leading nowhere. Many cosmonauts mill about in the short tunnel which leads to an obelisk similar to that seen in 2001: A Space Odyssey. No missions or odd jobs take Crypto here, nor are any pick-ups located here. It appears to be a 2001-related Easter egg.
- Ironically, it's name implies it has to do with The Sun, and not The Moon.