- Not to be confused with Terrain.
Arknights takes place in an alternate science fiction/fantasy hybrid world named Terra that is identical to our own, but with many key differences explained below.
Terra is ravaged by Catastrophes; various large-scaled natural disasters of such destructive scale that much of Terra's inhabitants are forced to adopt a nomadic way of life through mobile cities instead of a sedentary one, with few exceptions. A crystalline substance known as Originium is left behind at the site of Catastrophes and are 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 towards Originium.
Terra is inhabited by two dominant racial groups; Ancients and Elders.
The technology level of Terra is almost similar to that of our own world, but noticeably more advanced though not too far-fetched. In regards to warfare, however, medieval weaponry (e.g. swords, spears, shields, bows, crossbows, etc.) are used most of the time; firearms do exist, but they use Originium Arts as the operating mechanism (since gunpowder was never discovered in Terra) and their projectiles are made of Originium, thus making firearms a rare sight with handguns being more common than long guns, the latter of which are exclusively used by the Sankta.
- Main article: Faction List#Nation-states
As with our world, Terra is divided into many nation-states, with most of them are parallel to those in our world.
- During a Q&A session, Arknights' producer, Hai Mao, confirmed that Terra's flora and fauna are different to that of our world's.