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Location: Milky WayShadow SeaIera System Third planet

Prerequisite: Horizon (mission) (Mass Effect 2)
Prerequisite: Priority: Thessia (Mass Effect 3)


Mass Effect 2Edit

A temperate world that hit the "sweet spot" for carbon-based life, Horizon has a nitrogen-oxygen atmosphere maintained by abundant indigenous photosynthetic plants and bacteria. While the native plants are very palatable to humans, the soil conditions are such that a handful of introduced Earth species have flourished, and the colonists must take strict care to prevent ecological disasters. Genetically engineered "terminator seeds" that grow nutritious but sterile crops to minimize outbreaks are the rule rather than the exception. Animals on Horizon appear to be exploding in diversity similar to during Earth's Cambrian period. Large flying insect analogs take advantage of the thicker-than-Earth atmosphere and low gravity to grow enormous. Microbial life has proven relatively benign; a series of vaccinations for the most virulent strains of soil-borne diseases is all that is required for a visit.

Mass Effect 3Edit

A temperate world that has hit the "sweet spot" for carbon-based life, Horizon had a nitrogen-oxygen atmosphere maintained by abundant plants and bacteria. Its soil is particularly compatible with Earth vegetation, and so a thriving human community has sprung up.

Horizon's population is in flux. A Collector attack in 2185 inflicted significant casualties, but refugees have been streaming to the planet since the Reaper invasion began. Since many land illegally, there is no way to accurately track population. Although many colonists resent the newcomers, others have embraced Horizon's new role. Advertisements for "Sanctuary," its main refugee center, can be seen galaxy-wide.

Codex EntryEdit

A typical Terminus colony possessing minimal tourist value, Horizon promises substantial economic opportunity especially in providing new products for humans and supplying the Turian Hierarchy. Surveyed 18 years ago, Horizon received pilot habitation four years later; the colony proper is now eight years old.

Blessed with verdant forests and abundant fresh water, Horizon maintains a colonial culture that thrives as a refuge from the increasing restrictions of Citadel-governed society. Horizon has attracted numerous dissidents, marginal people, and fringe-dwellers from across Alliance space.


Mass Effect 2 Edit

Mass Effect 3 Edit

Trivia Edit

  • Despite being described in the Codex as a Terminus systems colony, Mass Effect 3's galaxy map shows the Shadow Sea Cluster as being in the Attican Traverse.
  • According to Mass Effect: Incursion, the population of Horizon was 643,315 in 2183.
  • In Mass Effect 3, Commander Shepard's line while departing from the planet ends with "I've had enough of this place.", similar to Shepard's last comment from Mass Effect 2 which is "I've had enough of this colony.".

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