Planet Cyran is designed to provide a unique challenge to KSP players in the form of a gas giant on which aerobraking is very dangerous, if not lethal.

Meet Cyran, a gas giant superheated by the radiation from it's radioactive core, and it's system of six moons: Infernas, Iltan, Dres, Kivlan, Sennim and Zerto.

Infernas is unstable, it's orbit is decaying and it's slowly sinking below Cyran's Roche Limit, and thus Infernas is breaking apart. The side facing Cyran is one huge inferno, with chunks of the terrain being pulled off towards Cyran. It is the debris of Infernas that has formed Cyran's rings.

Iltan is a beautiful golden moon, basically one huge beach. It has a breathable atmosphere and calm, blue oceans, as well as a nice temperature.

Dres hasn't just been moved to orbit Cyran, it has been remade as well to be a more interesting target with a crimson-gray surface, steep ridges and various craters.

Kivlan is a cyan moon with a deep blue atmosphere that seems to have a calming effect on Kerbals. It's a dream of endless hills.

Sennim is a bizarre world, it has oceans of liquid Mercury and signs of life have been found as well. Who knows what may be happening deep within that green atmosphere...

And last but not least, Zerto is a large, captured asteroid. It has a retrograde orbit, and while it has a partially exposed rocky core, it also has an outer layer of purple... stuff.