Gas Giant Campaign Setting
The 6 "worlds" all orbit the Gas Giant "The Mother". The star at the center of the solar system provides light and heat, thought "The Mother" also provides some as well as protection from the radiation from the star.
The 6 Worlds each have a different type of dominant lifeform, which explains the different types of races.
Each world is slightly different in composition and dominant climate, which influences the evolution of each planet's primary life-form.
Each world is between half as much as to 20% more mass than Earth.
Moon 1: Lizards & Dragons; Earth-sized
Moon 2: Dwarves; Earth-sized
Moon 3: Oceans; 20% more mass than Earth
Moon 4: Orcs & Goblins; 15% more mass than Earth
Moon 5: Fractured w/ Elves & Humans; Earth-sized
Moon 6: Shadow; 75% as much mass as earth