Austin's Aegis System

= Inner System =

Aegis I (Mining World)
Small, hot, rocky planet just barely liveable with use of standard survival suits and respirators. Mining operations are primarily undertaken by prisoners, with the better behaved being inducted into the PDF; a remarkably resilient force who excel in at fighting in extreme environments.

Mid Imperial tech level

Aegis II
Large rocky planet with poisonous atmosphere. Limited Mechanicus-operated gas harvesting aerostats sit in the upper atmosphere, providing fuel for vessels visiting the inner system.

= Mid System =

Aegis III (Civilised World)
Warm, wet world with extensive wetlands and river basins, gradually becoming more poisoned by the ecumenopolis housing billions of Imperial citizens.

High Imperial tech level

Aegis IV
Modestly sized gas giant, home to a small shipyard and Mechanicus outpost from Gara I.

Aegis V (Fortress World)
Expansive rocky planet with a thick but pure atmosphere. Ice sheets and tundra cover much of the more polar latitudes, moving down to large swathes of boreal forest and dry continental climes. Most of the planet's water is in one sprawling inland sea, with the opposing side of the world being dry and mostly barren.

A fortress world as long as Imperial records stretch back, Aegis V has been prepared with a vast underground rail network linking every major command post, munitions dump, barracks, and bunker on the planet. Strategic demolition charges are prepared to destroy sections to deny them to the enemy, and every regiment raised on Aegis V is as skilled at fighting in tunnels as they are in the outdoors.

High Imperial tech level

= Outer System =

Asteroid belt
Vast expanse of asteroids orbit the outer reaches of the system