Taking the points made in Generic: Government Types what might a fantasy version of the Traveller system look like?
In a fantasy version you’d roll per region rather than per world so say population = 2D6 divided by 2 and rounded down giving a range of 1 to 6
(which in Traveller is the number of 0s in the total populations so population level 1 = 10s of people, level 2 = 100s of people, level 3 = 1000s of people etc.
with DMs of say
- coastal fertile river valley DM+3
- interior fertile river valley DM+1
- temperate hills, woods DM-1
- plains, steppe, forests, swamps, desert DM-3
- mountains DM-4
then the government table might be 2D6-6 plus population level
- 0 none
- 1 clans or corporations (forestry, mining)
- 2 small tribes (mixed monarchy)
- 3 large tribes (mixed monarchy)
- 4 feudal – monarchy/conquered tribe
- 5 nation / city state – monarchy
- 6 nation / city state – corrupted monarchy
- 7 nation / city state – oligarchy
- 8 nation / city state – corrupted oligarchy – aristocratic or mercantile or religious
- 9 nation / city state – democracy
- 10 nation / city states – corrupted democracy
- 11 nation / city states – dictator/usurper
- 12 nation / city states – bureaucracy
corrupted systems will contain elements of civil war / repression.