Oddworld is the name of a planet that serves as the setting for all current games in the Oddworld series. It is several times larger than Earth and features multiple continents, although the continent of Mudos is the only one that has been explored in the Oddworld franchise to date.
Mudos, and presumably Oddworld as a whole, hosts incredibly diverse ecosystems supporting a multitude of species of flora and fauna, many of which have evolved to fill highly-specialized niches shaped by both natural and artificial influence. The geography is also quite varied; tall pine forests, arid rocky deserts, vast oceans, gnarled caverns and smoggy industrial zones are some examples of terrain depicted in the franchise.
Destruction of the environment is a recurring theme on Oddworld; species must continually fight for their short- and long-term survival in the face of encroaching industrialized civilizations. Large tracts of unspoiled land have been increasingly re-purposed by more technologically-advanced species as engines of mass-production; pollution in these areas is highly concentrated and typically takes a heavy toll on the surrounding regions and their inhabitants. Natural resources are consumed quickly and without thought to preservation or sustainability.
Scrabs and Paramites, two prominent examples of apex predators native to eastern Mudos, would likely be considered endangered species due to excessive harvesting of their populations as meat-producing livestock; a third species known as Meeches had already been driven to extinction by the time Abe's Oddysee takes place. Slogs, another notable dog-like predator, are more often found in captivity than in the wild. Slimy, carnivorous worms called Fleeches are often kept as pets until they reach maturity, and are subsequently disposed of via the sewage system; as a result, large colonies of overgrown Fleeches infest many subterranean areas of eastern Mudos. Only one riding animal species is known to exist: the elusive and ill-tempered Elums, which are also sometimes slaughtered for their meat.
Western Mudos hosts several of its own unique animal species, such as Slegs, the larger and hairier cousins of Slogs. Many smaller species in this region are captured for use as "Live Ammo": literally living ammunition intended for use in crossbows and other projectile weapons. Fuzzles, one of these ammunition species, are present throughout both regions of Mudos.
Several sentient species have also emerged on Oddworld in various states of cultural, technological and spiritual development. A shamanistic race of bipeds called Mudokons lost much of their culture as slaves under the yoke of the Glukkons, a highly-industrialized species of wealth-obsessed entrepreneurs believed to be native to a different, unknown continent on Oddworld. Nearly all commerce in Mudos is dominated by the Magog Cartel, a consortium formed by the wealthiest and most powerful Glukkons.
Security for Magog-controlled facilities is typically handled by the militaristic Sligs; green, legless thugs who wield automatic firearms and require mechanical augmentations for mobility. Sligs are social creatures and often keep Slogs as pets and sentries, although full domestication is impossible due to a slog's voracious appetite for raw meat.
A diminutive but intelligent aquatic species known as Gabbits also struggle to avoid extinction at the hands of the Vykkers, an inquisitive race of researchers who possess advanced medical technology and are known to hunt Gabbits for their precious eggs. Sadists by nature, they also enjoy performing dangerous experimental surgeries on any test subjects unlucky enough to be captured by their airborne research facility, the Vykkers' Labs.
Oddworld: Stranger's Wrath reveals that previous Oddworld titles had taken place exclusively in the eastern regions of Mudos, while Stranger's Wrath explores an area far to the west. A new set of intelligent species was introduced for the western region, most notably the Clakkerz, a rapidly-expanding race of flightless avian settlers and homesteaders, and the amphibious Grubbs, an increasingly-marginalized tribe that shares some cultural and physiological similarities with the Mudokons.
Less prominently, massive Steef herds also once roamed these lands and served as noble protectors of the timid Grubbs until a rapid Steef depopulation occurred, driven primarily by the lucrative bounties paid for Steef heads. Few enough now remain that the Steef are largely considered extinct by other local inhabitants.
A myriad of other species collectively known as Outlaws also inhabit western Mudos, their only unifying traits being a penchant for violence and an utter disregard for authority.
Five moons are thought to orbit around Oddworld, although only two are depicted specifically in the franchise: the Mudokon moon and the Gabbit moon, patron satellites of their respective races that bear the hand- or footprint of that race. This may imply that the three remaining moons are related to other, heretofore unknown "chosen" races inhabiting Oddworld.