Planetary Tiers

Planetary Tiers are a system of measurement on how habitable a world is. The Higher the Tier the more habitable it is.

Tier 0
Tier 0 refers to the planets that are not able to support life without artificial means. these are usually barren worlds that have no atmospheres or are too extreme for colonization.

Tier 1
Tier 1 are worlds that serve as outposts and fueling stations for the galactic traffic. These Planets are usually artificially sustained. However a natural tier 1 may have an environment that can be terraformed.

Tier 2
Tier 2 planets are planets that are closer but not in the Goldilock's Zone. these planets may have some natural life on them, however primitive and limited to plants and floral life.

Tier 3
Tier 3 planets are within a Orbits' Goldilock's Zone. These are the typical worlds that have breathable air, and drinkable water. They are rare, but serve as Empire capitals and homeworlds to certain races.

Tier 4
Tier 4 is the absolute Highest tier a planet can go. These are located within a Goldilocks' zone, however they are cesspools of natural life. The rarest of the rare, these planets are highly sought after for resources and expansion. A handful are known to exist, however they are one of the absolutely most defended planets of all time. Invasions of these planets are unheard of and often brazen, leading to the aggressor's defeat.