It's (generating life on gas giants) part of RTT world generation. If the system is above a certain age, roll a d6 for each gas giant, on a 6, there's life. Roll 2d6 to determine complexity of life, with 12 being sophonts.
I find this generates life a little too often on gas giants for my taste, so I change that first 1d6 Roll.
I find this generates life a little too often on gas giants for my taste, so I change that first 1d6 Roll.