As stated above, the game takes place in an alternate 21st Century Earth.
In 1994, instead of the Shoemaker-Levy comet impacting Jupiter, it instead impacted one of Jupiters' moons, shattering it into numerous fragments. These prompted extensive scanning of the outer reaches of the solar system. This resulted in the detection of a formation of cometary bodies that were on numerous impact vectors toward the inner planets of the Solar System, some travelling at extremely high speed. One in particular, named 'Heaven' by the astronomer that located it was theorised to be travelling at a significant proportion of the speed of light. With little recourse to intercept the object, the United Nations convened and drew up a plan for the survival of the human race.
However, the plan was flawed, and many security leaks allowed it to be leaked - incomplete - to the public, and mass panic followed. While some order was restored, it came at a cost, and ended in the plans not fully being followed through. As such, the UN itself was weakened and fractured, with many member states removing themselves from the assembly.
Private corporations, previously unheard of, stepped up to the plate and presented their own alternatives, adopted by many countries in return for allowing controversial research projects (such as those into human and animal enhancement and other restricted technologies, as well as issues related to patent laws and manufacturing rights) to be carried out on their soil.
All of this was swept aside, however, as the asteroid impacted Earth on November the 12th 1998. The asteroid released the equivalent to several
billion megatons of TNT. Hitting in Antarctica, the impact immediately caused catastrophic Earthquakes and Tsunamis that wiped out over two billion people on the planets' surface. Global sea levels rose dramatically, and many industrial, economic and population centers were wiped out in the chaos and devastation, resulting in a huge shift in global economic priorities and population levels.
Almost immediately after this, more people died due to increasing riots over food, medicine and aid shortages. Many of these conflicts exploded into ethnic and other conflicts, before the United Nations began to mobilize itself as a global government, following a hastily signed treaty in September 2004 (the September Agreement).
Obviously, not all nations agreed on this, and many split away, leaving the UN Government as something of a less-than global initiative.
Ocean power and transport became a much more important commodity in the water-logged world, and naval power received a new focus as part of the UN Forces (UNF). The UNF managed to bring some kind of stability to many territories, while others turned to the corporations that had established themselves and the nations they held territory in for guidance, forming their own alliances.
Meanwhile, the UN continued to attempt to rebuild, slowly piecing together the bare bones of the world. By 2010 the world had begun to return to some form of normalcy, but the butchers' bill was devastating: almost
half the world's population had been killed by the Heavenfall and the following violence, disease and starvation. The UN approached former members for aid and assistance and to offer membership, but the efforts were rejected, often resulting in clashes and tense standoffs.
The situation grew worse over the following years as the non-UN Nations began to build new facilities for research, power generation, defence and other such concerns, and often lead quiet initiatives to recruit other nations, as well as sending spies and other agents to gather information on the UNF. The concerns about hostile takeovers, pollution and the like result in further brushing up between the groups, especially as the non-UN nations begin to adopt increasingly large and advanced armed forces.
Finally, a conflict over land and resources turned into a shooting war, which ended in an all out battle between UNF naval forces and non-aligned nations aircraft. Civilians from both sides were injured, and the crises was turned to a meeting in Geneva. Shortly after this began, the Geneva UN HQ was attacked by an orbital strike. Simultaneously, numerous Strategic Weapons sites, such as bomber and ICBM launch sites were attacked, along with many front-line aircraft and naval bases, wiping out much of the UNF's key military units in one strike.
Simultaneously, the non-aligned nations declared themselves as the United New World Order, or UNWO, and declared themselves out to remove the UN's control of the world, and institute a new and forward-looking government over the UN's, one that would seek to remove the problems of the past, such as the failings of the UN in the aftermath of the Heavenfall, and the numerous other failings of the UN over the years. They intend to do this by eliminating their military, political and financial power, and taking over the control and guidance of international government in their own image.
The world itself is thusly shaped by the Heavenfall incident. A vast majority of the worlds' low-lying and coastal cities are now underwater, or at least partially so. Many capital cities have been relocated to inland cities, and industries have similarly moved on to new places. The earthquakes and volcanic activity have further resulted in great devastation, along with the massive conflicts and violence in the first decade of the 21st century.
Many well-known cities and regions of the world have now been consumed by flooding, leaving much of the worlds best known art, architecture and skylines ruined by flooding, and the skeletons of buildings rising from the seas off shore.

The global population has also decreased vastly, leaving large areas of land unclaimed and empty, with many cities and towns empty shells that are decaying and wasting away, damaged or destroyed by conflict and the global upheavals. Nonetheless, what is left habitable is at a premium, with many areas in competition for healthy farming, fishing or building land, and massive projects underway to irrigate huge areas, build new cities and more.
High technology and science are believed widely to be the way to help mankind out of it's current spiral toward extinction by both governments and individuals - but there is also an undercurrent from some more radical or fanatical quarters (i.e the more out-there religion sects) that humanity has transgressed somehow, and is only receiving what is 'expected' for so many sins.
Others still see survival as a gift and a free pass to live a hedonistic lifestyle, while others see it as a chance to make a new start at life. All in all, everyone is scrabbling to survive.
New technology is emerging at a furious pace. Computer technology has advanced in leaps and bounds, with networking and data storage capacity growing almost monthly. Processing power is also increasing exponentially, and physical media is virtually obsolete as the Internet has linked up almost everyone worldwide, especially via the use of satellite capability to transmit data.
Power generation and storage has been increasingly focused on renewable energy, with solar, geothermal and tidal power being increasingly looked to for solutions to new building projects, such as the up-and-coming Arcology concepts for cities.
The UN GovernmentThe UN Government and UNF is a coalition of the member nations of NATO, the EU, Japan, Australia and New Zealand, most Central American and Carribbean countries, Columbia, Israel, India, South Korea, Argentina, Peru, Taiwan, Thailand, Saudi Arabia, Russia, the UAE and South Africa, as well as a number of other countries of note. They have organized into a unified command structure for their military forces, and have a loosely democratic government based on a senate of international leaders and politicians. While it is rough around the edges, it is beginning to work.
The UNWOThe UNWO consists of the majority of other non-UN countries, especially including Brazil, Argentina, Chile, China, Iran, Iraq, North Korea, Egypt, Libya, Cuba, Nicuragua, Vietnam, Burma/Myanmar, Laos, and the Phillipines, among others. While they are more numerous than the UN, they also have more internal conflicts and - apparently, at least - a lower overall level of technology and sophistication, though this assumption is in part what lead to the victorious strikes on the UN forces and their later crippling in the face of the UNWO, as their equal and in some cases greater level of sophistication is revealed in one fell swoop.
Independent CountriesNot all countries are part of one group or the other, or do not play an active or engaged part of one group or the other, remaining neutral or providing only logistical or material support, rather than engaging in open combat.