1. Add a new command (or skill use) called RULE. Any stack leader may
at any time RULE (or USE RULE) for any number of days.
2. When a stack leader issues a RULE command there is an automatic
check whether any other unit in the same province is ruling right
now. If there is automatic combat occurs between the current RULEr
and the unit issuing the RULE command (and their respective stacks).
The winner of the battle continues to RULE, the loser flees (and
interupts his RULE).
3. At the end of each month the unit issuing the RULE command
receives an amount of money depending on the population of the RULEd
region. Ten times the number of work jobs in gold seems a reasonable
a) This system can be refined by taking into account arguments to
RULE like eg. taxation levels.
b) An alternative to 2. is to have RULE commands simply fail if there
is another RULEr. A new RULEr would be expected to attack and remove
the old RULEr by an explicit ATTACK if that is what he really wanted.
This would prevent accidental attacks. The reason I'm not suggesting
this is that it would allow a ruling faction to play all kinds of
silly games of stealthy units quickly exchanging the RULErship among
themselves which could allow such a faction to prevent even a much
more powerful faction to take over for months (or even indefinitely).
Hence auto-ATTACKs. If you want to be the RULEr of a province or
depose an old one, be prepared to take risks.
c) If you use the above algorithm to establish rulership all kinds of
other things can be tied to it, but other people have suggested
enough possibilities for that.