System Builder

System Age

The first step is to determine, broadly, how old your star system is. The following table has a bias toward creating an "established" solar system outside of the Archaean and Hadean period of planet formation. However, it is possible. Different eons of planetary formation will also impact whether life has had a chance to develop on the planet. The longer the system has existed in the Main Sequence, the better chances life has for gaining a foothold.

System Age Table

1d100	SYSTEM AGE	MODIFIERS
01-04	2d10x10 Million Years	BIO set to 0; all planets are Protoplanet types. -20 SIZE on each planet
05-15	1d10x100 Million Years	BIO -40
16-20	1d4-1 Billion Years (minimum 1 Billion)	BIO -10
21-45	1d6 Billion Years
46-70	1d10 Billion Years
71-85	2d6 Billion Years
86-94	2+2d6 Billion Years¹	BIO +10
95-00	3+2d6 Billion Years¹	BIO +15

System Age Notes

¹ This could theoretically create a star system believed to have existed before the Big Bang Primordial Singularity (which was somewhere between 13.8 and 14.6 billion years ago). Science should have a fun time trying to explain that one!

Creating Stars

At the heart of your solar system will be at least one star (possibly more, or perhaps, a post-star). This engine does more to influence the makeup of the system than any other piece within the system.

Go Big or Stay Small?

Large, hot stars usually burn through their fuel and explode before a planetary system forms an environment conducive to life. Usually, they blow all the material components for making planets into the outer system or even out of the system altogether. On the opposite end, small, cool stars may last for a long time, but they lack sufficient gravity to hold onto much material (or planets) in the outer system. Large planets tend to escape from them. Stars also vary in size, even in the main sequence (the period when a star is considered most stable).

Picture in Binaries

When you are forming star systems with multiple stars, science is showing us that most of these systems are made up of multiple binary systems that happen to be close enough to be considered the same star system. It is unlikely that multiple stars will orbit only one star. However, the system below is flexible enough for you to create such a system if you wanted to. Adjust the policy of "one parent, one companion," to allow for multiple companions.

Trinary, Quintuple and Septuple Systems

As above, build in Binaries, but in the case of the "odd man out" star, that companion can either orbit one of the binaries, or the whole crazy system in some distant orbit. Treat it as a second companion star.