From Outscape Wiki
Mountain giants are one of the most common species in a galaxy. It's a wonder how they've become so widespread in the galaxy, but their groups can be observed on arid planets located hundreds of light years from each other.
Mountain giants are incredibly huge. The average size of an adult male is 25-30 meters in height, with weight more than 40 tonnes. Discussion about how smart they are is still in progress. But the most important feature is that individuals grown up separately from wild giants, can be easily trained to perform hard work and military goals. They significantly boost planet production. In-Game Description
Mountain Giants are a minor faction that can be found throughout a galaxy. They prefer colder planets with plenty of land. When a planet with a native Mountain Giant population is colonized, their population automatically joins the colony and can contribute to the planet's development.
Benefits to a Colony
A colony can utilize the formidable physical strength and increased military enlistment of a Mountain Giant population to bolster their Home Guard. In the A3 Skirmish galaxy, all Mountain Giants are part of a planet's home guard, significantly increasing the strength of ground defences. Additionally, the time required for the construction and upgrading of structures on the planet is also decreased by 20% (60% in A3 Skirmish).
If such a planet also hosts a Shipyard, ship construction times will also be reduced by 20% (but ship upgrades will not). As Mountain Giants typically inhabit large worlds with high land fractions (and therefore with high maximum populations), such planets can be particularly valuable for hosting Tier 4 Shipyards, to reduce the long build times of Dreadnought-class hulls and the associated planetary infrastructure needed for their construction.
Mountain Giants are also 4.5x less affected by happiness penalties arising from taxation, and so can be taxed at a higher rate than other organic factions on the same planet. However, their small starting population and very slow growth rate make this only a minor benefit.
Humans have reasonable synergy with Mountain Giants, but Ripchee players may find them less useful, as Mountain Giants prefer climates and land/sea balances very different from ideal Ripchee growth conditions.