Quite possibly the best hard SF setting out there.
There is no Faster-Than-Light space flight - but the vast reaches of the solar system form a new frontier for the human species and its various offspring. From the busy Earth-Lunar space and its great Lagrange colonies to the anti-matter factories of Mercury, from Chinese Mars to the US He-3 mining concerns around Saturn, from the homesteaders of the Main Belt to the Gypsy Angel comet herders of the Oort cloud, all are a grand testament to the adaptivity of the human spirit - and form.
No one has encountered any sapient alien species - but humanity has started creating new species of its own. Human genetic engineering has revolutionized the way we look at our own species - from slight "upgrades" that only make the children a bit healthier than their parents to radical parahuman designs that adapt humans to different environments, like the artic wastes, the oceans - or space itself. There are sapient "uplifts" of various animal species. There are "bioroids", artificial humanoid androids constructed for specific purposes. There are artificial intelligences, some of them sapient. There are "ghosts", humans who have destructively uploaded their brains and now continue to exist as sapient pieces of software - effectively immortal as long as they can be restored from backups. And many of these entities are far more alien than most "rubber mask" aliens commonly seen in science fiction.
Technology has progressed rapidly. Care was taken not to violate realism when creating the technology for the setting, which means that there is no "miracle tech" - but the technology that exists has been exploited by society in ways never dreamed of by the science fiction writers of old. Everyone and everything is connected to computers all the time, and every device has a dedicated computer on its own. An exta layer of "Augmented Reality" is put over the world we see to provide additional information. 3D printers can quickly create almost any device you might need. Unobtrusive and ubiquietous surveillance can make a country almost free of violent crime - or a oppressive hellhole in ways not even Orwell could have conceived.
Three Great Powers powers - China, the European Union, and the USA - vie for influence, while other up-and-comers - India, the South African Union, the Pacific Rim Coalition, the Islamic Caliphate and the Transpacific Socialist Alliance - try to carve their niche in geopolitics. But in the end, the future of humankind will likely determined in space...
