Styx possesses 1.1 times Earth's mass, and 1.4 times the radius.
Styx is cold and wet, with large fogs covering much of the planet's surface. The land temperature is very even, around 10°C all over, but the poles are around -40°.
Styx rotates very slowly, a day taking around 40 hours. It has zero axial tilt, and as such no seasons.
Styx's atmosphere is tolerable, with 80% nitrogen, 16% oxygen, and much methane from the marshes. This would create an intolerable greenhouse effect were Styx not so far from the Hellstar.
Styx's continents are arranged in one large supercontinent. The planet is tectonically dead, so the continents do not shift. Much of the land is basalt, which is impermeable so water sits on the surface, creating boggy land.
Daemons have colonized this planet in huge numbers, virtually taking over the surface. A non-demonic species known as the Rennites once lived on the planet, but are now almost extinct. Around a hundred or so still survive as rebels on the planet.
Recently, the Rennites and the Angeli allied with each other in order to take back Styx. How long they will hold on to this territory is unknown.
Twisted marsh trees are also present.