I want to suggest something that can be seen in our universe. Tidal Locking. I won't go into scientific details but what it basically means is one side of the planet is trapped in darkness forever, and the other is trapped in light. How this can be done in game would possibly hard to code, however each worlds have set sizes. It could be coded that half of that size is dark and half is light. Because of this, the eternal dark world may have completely bizarre, or barren biomes compared to the light world which would resemble normal or thriving biomes. Because of this eternal darkness, the dark side of the planet would be in perpetual winter, acting like a snow planet. The transition from the dark side to the light side is relatively normal, and the middle of the light side is mostly desert. Thus, you already have an idea of how the world may look like. Forest and Jungle is interchangeable in this situation. These planets can only spawn on threat level five and higher. I think this could bring interesting diversity to a planet. Here's a link that inspired this idea. http://en.wikipedia.org/wiki/Tidal_locking
+1 the planets so far have a good variety of flora, but other than that... more planet variety would make exploration so much more fun. thinking of 'Spore' here
A good idea, but then you may get a situation where a moon is tidally locked to the systems star, which wouldn't happen. Also, worlds that are tidally locked are usually very close to their parent star.
