The steps would look something like this:
- Start game as usual with Earth race - make sure to choose the population you want to have as this influences the other NPRs that generate at game start.
- Turn on Spacemaster Mode (SM).
- Create a race on Earth from the System View window and check the box to create them as a NPR with whatever settings you desired.
- In the System View window, select Mars and try to create a race.
- If this doesn't work:
- There will most likely be a popup indicating that the conditions on Mars are too harsh to allow this (if not, check that SM mode is toggled on).
- You will have to use the Modify Body popup to temporarily make Mars friendly enough, create a race there, and then change the environment back if you desire this.
- Make sure you create your Martian race for the original or intended environment settings, not the temporary ones.
- Change back to the original human race on Earth and delete them, so only the NPR remains.
The other option is to start the game as usual, but create the initial player race as Martians (with the right environmental tolerances, etc.) and then create a colony on Mars and move everything from Earth to Mars (most of this can be done with SM mode, a few things may require DB editing or some clever SM tricks). Then create a NPR on Earth as above. The advantage of this more tedious approach is that you don't have to play around with modifying the Martian environment, and you don't have to delete a race - I have suspicions that both of these operations are prone to causing problems in the DB file based on my past experiences.
You could also go the route of playing both Earth and Mars as player races, which may offer more satisfying gameplay once you wrap your head around playing both factions as the NPR AI is rather limited in matters like diplomacy, tactics, economics, and not being a genocidal maniac.
