Arc (in Orcish Ur, or Elvish Lenos) is a small planet orbiting a yellow gas giant. The name is archaic, meaning "home" in an extinct and forgotten language. It consists of various continents and islands, including Eamae, Thlea, and Valethal in the central supercontinent, Pheaohr to the East, Tahhraeae to the West, as well as the arctic continent of Alsres and the antarctic continent of Afralses. Beneath these sprawl the unfathomable reach of the Underdark. The majority of the surface is covered in oceans, through which countless islands are scattered. Arc's environments vary widely, ranging from frozen ice sheets near the poles to deserts and tropical jungles near the equatorial regions.
Arc orbits the planet Mithraea, the fifth planet of it's sun. Mithraea has numerous satellites as well as three rings. The first and innermost ring is a glassy obsidian in colour, the middle ring is a gleaming silver, and the outermost is comprised of pale crystal. Arc itself is orbited by two moons of it's own, Thoceath and Thothe.
One rotation of the planet is known as a day, and one revolution around the sun takes 300 days, a year. The year is divided into twelve months of 25 days each, and it passes through four distinct seasons.
- Eamae: The easternmost portion of Arc's central supercontinent, a diverse landscape inhabited by numerous races and cultures, including humans, dwarves, elves, halflings, and gnomes, as well as many monstrous races.
- Thlea: A mostly hot, arid realm. It is significantly less developed than Eamae and and Valethal
- Valethal: A vast forested land, known for being the homeland of the elves.
- Pheaohr: A vast desert region.
- Tahhraeae: An exotic land known for trading and steeped in ancient history.
- Alsres: The harsh frozen north. Currently unexplored
- Afralses: A massive southern ice cap. Currently unexplored.
Many races inhabit Arc with varying levels of sentience.
- Humans: The most widespread and versatile race. Can be found almost anywhere on Arc.
- Elves: The first race of intelligent beings. Slender and graceful, their natural lives can span a thousand years.
- High Elves: This sub race of elves resides within the tree-wrought cities of Valenthal. As a result of their near identical physiology to each other, they, culturally, have taken to wearing masks to differentiate from each other.
- Wood Elves: A simpler sub race of elves who share a deep bond with nature.
- Drow: Also known as Dark Elves due to their gray fleshtones and red eye coloration. They keep underground, common to the Underdark and the Black Mountain, and have developed a sensitivity to the sunlight of the surface world.
- Dwarves: Mountain dwelling people known as master smiths and artisans.
- Duergar: Evil, gray-skinned dwarves who often live near the Underdark.
- Gheladan Dwarves: Hardened dwarves who live beneath Mt. Gheladan and revere it as a deity.
- Halflings: A short statured peaceful people. Generally live in hills.
- Gnomes: Often found living alongside dwarves. Known for being intensely curious and intellectual.
- Orcs: Easily noticeable due to their green to gray skin, lupine ears, lower canines resembling boar tusks, and their muscular builds.
- Monstrous Races: Arc is also inhabited by numerous types of monstrous races, sentient or wild.