- Not to be confused with Terrain.
The world of Terra is similar, if not identical, to our Earth, including having an oxygen atmosphere, a more-or-less indentical gravity and atmospheric pressure, and carbon-based lifeforms; even humans from our world will have no issue living on it if they are somehow brought into Terra. However, what sets Terra apart from ourr world is the Catastrophes – cataclysmic natural disasters which force much of the Terrans to adopt a nomadic way of life through nomadic cities instead of a sedentary one. A crystalline substance known as Originium is left behind at the site of Catastrophes and is widely used as a source of energy and the catalyst for magic-like Originium Arts. But at the same time, it is capable of causing a terminal disease known as Oripathy from direct or prolonged exposure which is responsible for much of Arknights' rather bleak tone.
Terra is predominantly inhabited by various races known as the Ancients, an amalgamation of humanoids with animal features and completely anthropomorphic animals. Other than the Ancients, Terra is also inhabited by Elders that seems to be a kind of Ancients that belongs to the ruling class of Terra. The Terran races have an extraordinary strength that could easily outmatch our world's humans thanks to their unique racial traits. Each race also has a different anatomy that requires extensive medical studies to fully comprehend. Aside from Ancents and Elders, there are deities or god-like beings like those who once ruled over Yen, eldritch demons inhabiting the tundra of Terra, and the Seaborn from the abyss of the vast ocean.
The flora and fauna of Terra are fairly similar to our world's with some notable stark differences. Terra's notable fauna includes canine "hounds," large "slugs," "metal crabs," "gloompincers" or "pincerbeasts," badger-like "sand beasts," and (giant) arachnid "rock spiders." In addition to these, there are animals that are analogues to those in our world:
- "burdenbeasts," referring to horses, donkeys, or other beasts of burden in our world.
- "cystybeast," referring to cattle (i.e., dairy cows) in our world.
- "fowlbeast," referring to the aves, or birds, in our world.
- "scalebass" or "fins," referring to fish in our world.
- "shells," a collective term for crustaceans and shellfish in our world.
- "tuskbeast," referring to other fierce carnivores in our world.
The technological level of Terra is similar to that of our own world, but noticeably more advanced to a limited extent. In regards to warfare, however, cold weaponry (e.g. swords, spears, shields, bows, crossbows, etc.) is used most of the time. Firearms and explosives do exist; however, both are Originium-based. Unlike those in our world, Terra's firearms use Originium Arts as the operating mechanism and fires Originium projectiles, making it more of a "magic wand" that could shoot out bullets. In the meantime, Terra's explosives use compounds that are derived from Originium. Consequently, this makes firearms an extremely rare sight in Terra, — more so than explosives — with handguns being in turn more common than more complex firearms. In fact, those rifles and advanced firearms are exclusively used by the Sankta. Because of different chemical composition, some of our world's chemicals may never be found in Terra, such as those that could fashion simple gunpowder.
Terra's astronomy and astrology is, once again, quite similar to our world's, albeit with some notable differences. The Terrans lack some technologies taken for granted in our earth due to their disinterest in exploring outer space. The dating system of Terra is identical to the Gregorian calendar in our world – even sharing the same month names (January, February, etc.) – but has a different year count, with the current Main Theme set during the Terran Years between 1096 and 1098. The major difference with our world is Terra possessing two natural satellites (i.e. moons) that are collectively known as the "Twin Moons" in various folklore; but so far, nothing is known about the star that acts as Terra's sun or other celestial bodies. It is even implied that the stars of Terra have, for some reason, likely industrial or light pollution, become harder to observe.
As of the current events of Arknights, much of Terra still remains uncharted and unexplored. These charted areas encompass various landmasses with different biomes.
On the topic of Terra's geography, much of the land is covered by arid deserts. Some places, however, are filled with temperate forests, fertile grasslands, and tropical jungles that are suitable for settlement. Mountain ranges are found in various parts of Terra such as Kjerag and the border between Kazimierz and an Ursus exclave. There are also various large lakes throughout Terra, such as one surrounding an island where Shamare was found. A giant inland sea is located between southern Victoria and the peninsula where Siesta is located. Surprisingly, there is also mysterious subterranean region which the majority of the Durin race inhabits, and it remains at large uncharted territory to the average Terran.
So far, very little information is given concerning Terra's "great beyond," with two regions acting as the borders between Terra's civilized world and terra incognita: the Foehn Hotlands in Sargon and the Northland in Sami and Ursus. In addition to these, the coastlines south of Iberia, north of Bolívar, and east of Higashi lead to the vast, unexplored ocean; Aegir is located somewhere south of Iberia's coastline.
Because of the awkward geographical isolation and the landlocked status of most countries, the concept of ocean is alien to most non-Aegirian Terrans.
- The hexagonal areas without color on the map above represent unclaimed territories/"no man's land," formally known in our world as terra nullius.
- The blank areas on the map above represent uncharted territories, or formally known in our world as terra incognita.
As with our world, Terra is divided into many nation-states, often being parallels to those in our world, or rather, amalgamated cultures which do not belong to merely one country or time period, but several at once — the most notable example being the pre-Columbian Mesoamerican and Middle Eastern influences of Sargon.
There are some Terran nation-states that are not elaborated in the game with some being likely defunct by the time of the Main Theme of Arknights. These include:
- Rus: Mentioned by Kashchey, Rus is likely a parallel to the Goths, Huns, and/or Vikings in our world.
- Kingdom of Agamemnon: Mentioned in Conviction's Archive files, Agamenmnon was founded by an artist and was claimed to have far more advanced technology than the rest of Terra, notably QR codes and trolley problems. It is now absorbed into present-day Minos.
- Dan: Mentioned in "Frost" furniture description of The Zen Garden set, Dan is possibly one of the three Oriental nations that Ceobe once ventured into and is likely a parallel to Korea in our world (just as Higashi and Yen being parallels to Japan and China respectively).
It is worth noted that the current geopolitical atmosphere of Terra is akin to the pre-World War I period where different nations rivaled each other for land and for power without very little restraint — prior to establishing our modern-day pacts and alliances. Most of these nations are made up of empires, kingdoms, or oligarchies that have been around for generations. Genuine, modern democracy is presumably impossible to achieve; even Columbia, the only democratic nation in Terra, is also conducing acts of imperialism onto other nations. As a matter of fact, human rights hardly seem a topic of concern to Terran nations, and chattel slavery is still effective in every parts of Terra such as Kazimierz. There are very few charities or other somesuch international organization aside from Rhodes Island that provides humanitarian aid in various war-zones or arouse notions of human decency. The only other known organization providing relief effort is the Contingency Contract system, and it is implied to be corrupt.
- Terra is a Latin word that is generally used to refer to earthly matters (e.g. "earth," "ground" and "world").