So as a bit of a SF buff myself, I thougt about more world generation options and came up with:
1) Star light spectrums. To quote http://www.solstation.com/life/a-plants.htm
So I'd suggest the following options:If comparatively more bluish or reddish light reaches a planet's surface than on Earth, photosynthetic plant-type life may may not be greenish in color, because such life will have evolved to different pigments in order to optimize their use of available and so color the appearance of the planet's land surfaces accordingly.
(...)"Plants" on Earth-like planets orbiting stars somewhat brighter and bluer than the Sun might look yellow or orange, and even look bluish by reflecting a dangerous overabundance of more energetic blue light. On the other hand, plants on planets orbiting stars much fainter and redder than the Sun might look black.
Autumnal to bluish colors. Main sequence stars brighter than the Sun (spectral types F and A and the very short-lived B and O) emit more blue and ultraviolet light than the Sun. Given sufficient time for Earth-type photosynthetic life to evolve (e.g., hundreds of millions to billions of years), planets around such stars could develop an oxygen atmosphere with a layer of ozone that blocks more energetic but potentially harmful ultraviolet but transmits more blue light to the ground than on the Earth. In response, life could evolve a type of photosynthesis that strongly absorbs blue light, and probably green as well. In contrast, yellow, orange, and red wavelengths of light would likely be reflected by such plants, so the foliage would have the bright colors found during autumn in Earth's deciduous forests all year round. On the other hand, some plants may reflect some blue light due to its overabundance and potential to "burn" photosynthetic organisms (e.g., like sunburn from ultraviolet exposure on Earth).
Darker schemes. A main sequence star that is dimmer and redder than the Sun (spectral type K and M -- red dwarfs) could have plants that absorb more red and infrared wavelengths. Red dwarf stars, which only have some 10 to 50 percent of the Sun's mass but comprise perhaps 85 percent our Milky Way galaxy's stars, radiate most strongly at invisible infrared wavelengths and produce little blue light. By absorbing the entire spectrum of visible light more completely, such plants might look black but any color might be possible. Whatever their color, however, such plants would likely look dark to humans because little visible light would reaches the ground.
A) Very bright star - blueish foliage
B) Bright star - red and gold "autumn" looking foliage
C) Sunlike star - earthlike green foliage
D) Dimmer star - dark green foliage
E) Very dim star - very dark grey brown or almost black foliage
This would add to the alien-ness of the world in a very visible way, but would not require much graphic work (can even be just recoloring the already existing terrain textures). Gameplay could either be left entirely the same, or non-erathlike light spectrum planets could require the player for example to pay extra upkeep until he researches some technology.
