Is there a guide anywhere to making your own solar system with your own race?
Quick and Dirty guide:
1. Start a game in SM Empire mode.
2. Turn Spacemaster on.
3. Go to System Details and generate a system.
4. Does it have either a Nitrogen-Oxygen world with no contaminants, or a Methane world with no contaminants?
5a. If not, gen up another system.
5b. If so, do you like the look of the system? If not, see 5a. If so, go to 6.
6. Select that world and click HW Minerals. This ensures the planet will have sufficient reserves of everything, otherwise you could be screwed in getting off the planet.
7. Click Create Empire.
More generally, I find that if you're doing an Oxygen race, you might actually be better off choosing on with somewhat lower gravity and temperature than Earth, because the majority of N-O worlds you're liable to run into are going to be snowballs of around -20 to -50 C and maybe 0.7G gravity. Especially in a Real Stars setting, where you get LOTS of red dwarfs which are hard pressed to give you worlds warm enough for bog standard humans. Non-Real Stars, you get a lot more A, B and even O stars which can have higher temps.
If you go Methane breathers, you're almost locked into having a temp range below -100C. Gravity can be highly variable, as you can get cold Methane worlds ranging from tiny moons to large worlds in the outer orbits of systems.