I have implemented Fertility(AKA glorified humidity if I have made any posts earlier on the topic). I basically have a value called humidity spread out from the sea which conforms to the terrain, the thing causing the big deserts is that the humidity value of the sea is changed by a noise function. If the humidity is over a certain threshold, then I say that the node is fertile. Not realistic at all, but seems to work.
In cases where the terrain is flat, and the humidity noise is high, you get stuff like the topmost image, which according the water level should be a desert, but instead appears to be a goddamn rainforest. The intent was to make planets have more varied terrain, I feel like I have succeeded.
And in case anyone is wondering, no, I in fact didn't do any work on the UI or actual gameplay. Sue me.
Are civilizations going to start off at the same point as the player, or will they be randomly generated as well? (or perhaps generated around your borders?).
If there are a lot of planets, it might be tricky to simulate all those civs sprouting up if your planet maps are large as well.
They will spread out from the player. Occasionally planets will rebel against you, or on a planetary scale a few people will just grab a bunch of your stuff and start a colony on the other side of the planet.
And indeed, having a bunch of planets with each having their own factions might be quite demanding. I will have to see how resource efficient I can make the AI.