A/N: These are own 'codex'-like entries in a style as it would be presented in the Mass Effect game and its official wiki.
The planet Arcadia is location, where my own LiS/ME fanfiction-crossover takes place, so I wrote the following article for background info about this place and scenario, which is greatly inspired by LiS, but influenced by ME, obviously ^^

contains no spoilers towards MEiS, ME, LiS; only a short prehistory for certain MEiS-contents.

Parts of featured content belong to Bioware/EA and Dontnod/Square Enix

For the article I used as a pattern for the following see: Mass Effect-wiki / Arcadia

Arcadia

Location: Milky Way / Exodus Cluster / Shambhala System / Third planet

Planet View

Orbital Distance 1.1 AU

Orbital Period 1.1 Earth Years

Keplerian Ratio 0.909

Radius 6182 km

Day Length 23.6 Earth Hours

Atm. Pressure 0.97 atm

Average Surface Temp - 67,8°C

Surface Gravity 0.92 g

Mass 0.811 Earth Masses

Satellites Selene

Colony

Species Human

Capital Arcadia City

Colony Founded 2153

Population 23 000 (2169)
9 000 (2183)
(Pop. estimate is pre-attack and today)

Description

As for an earth-sized garden world with a breathable atmosphere consisting of nitrogen and oxygen, Arcadia is suspiciously unknown throughout the Alliance and interstellar space. Due to its slightly larger distance from its parental star Shambhala and its cool solid core the planet is mostly covered in ice. Only its equatorial regions allow organic life, which therefore thrives even more in this area.

Arcadia was once considered an old, dying garden world, since its surface temperature had steadily fallen during the last few million years, which caused the already small corridor of the survivable belt that is the equator to shrink even further. Recent analyses however proof, that the short but intense output of manmade greenhouse gasses will cause this temperature decrease to come to a halt in near future. This achievement though comes with the price, that Arcadia's nature and wildlife are still threatened by humanity's invasive measures and pollution of its fragile ecosystem.

Although Arcadia possesses plentiful known deposits of platinum and several other valuable minerals, it was barely noticed until the very end of humanity's first wave of colonization: Due to its great distance to the next mass relay in the Utopian system, it can take weeks traveling to this remote system, and therefore becomes unprofitable for necessary long range transport routes. In spite of that, in the year 2157, several thousand colonists finally tried their fate, concentrating their settlements at the most promising location, today known as Arcadia City, as it is the planet's only city ever founded.

Confronted with the question of why this world is still so underdeveloped and unknown to the galactic publicity and corporations, Alliance officials often claim, that the overall harsh environment and remote location of the planet discourage most colonization efforts. Arguing that it is simply outshined by closer more convenient colonies, such as Eden Prime. The unofficial truth however is, that the Alliance military wasn't able to repel a surprise pirate attack on the colony in the year 2169, as strategists never considered an assault on such a remote backwater colony. By the time alliance reinforcements could arrive, the unusually brutal attackers had already retreated after effectively massacring or kidnapping approximately 1800 citizens of the planets population. What they left behind was barely more than a devastated ruin stripped of large parts of the despairing population.

In the aftermath of the onslaught, many of the remnants of the population considered emigrating or actually left, effectively giving up on the colony. Industrialization campaigns got discarded by most companies, but a handful. Second to none of them is the 'Prescott Planetary Mining Company' (PPMC), today Arcadia's largest private corporation and virtually unrivaled profiteer of the planet's vast mineral deposits, becoming a small light of hope after the catastrophe.

Until today, Alliance internals to some degree even concealed the colony's existence, not being able to accept the defeat it had to experience. In 2183 however the planet eventually regains Alliance military's attention as a terse distress call once again appeals for help...

Trivia

- "Arcadia is a region of Greece located on the Peloponnesus peninsula; in ancient times its pastoral beauty became a byword for idyllic, unspoiled wilderness."
- Mass Effect-wiki (article Arcadia; 28.01.16)

- Shambhala, the star Arcadia orbits around, is named after a mythical paradise-like kingdom in Tibetan Buddhism, also known as 'Shangri-La'.

- the name of Arcadia's moon Selene is deduced from the mythological ancient Greece goddess of Earth's moon Luna.

- the planet's physical data actually does not make sense. It is certainly not even possible in physical terms of logic to bring such a planet in existence. The numbers were simply thrown together by the lazy author to at least fit into the story of 'Mass Effect is Strange'.

Props to all ME-fans, who read this article with Neil Ross' (aka. the voice actor of the original codex entries) voice in mind. I at least did, whilst writing this ^^

Btw, you might have noticed that Arcadia is, in fact, a real planet in the ME-series. It is a minor side planet, comparable to RL Venus, though, so I had to make major changes to in order to make it fit into my story of MEiS.

Update 03/18/16: I just realized that a solid planetary core, like the one Arcadia is supposed to possess, in fact isn't quite realistic. A liquid core (like Earth's) is actually necessary to create a magnetic field in order to protect a planets inhabitants from cosmic radiation.
I know that this is a fiction and I don't really need to consider such 'tiny' facts, but I still want to point this out, because most sci-fi universes/stories just give a sh*t about realism and I don't want contribute to those and their tendency to increase people's ignorance. *cough* 'Gravity' *cough*
I'm already considering to change this little fact, although it would take me also to change parts of MEiS. :/