[Freeciv-Dev] (PR#5555) logic of city-bribing + lose gold if bribe fails

["Genevieve Gracian" <ggracian@xxxxxxx>]

Hello, 

This come from a more general ticket about diplomats I sent a while ago
about how to make diplomats becoming less-powered units (#4593 Diplomats).

The idea is that the cost for bribing a city can be lost for the attacker
even when the bribe fails. That brings some questions on how works exactly
a city-bribing.

The expected effect of the main subject (lose gold even if bribe fails)
is to make city-bribing a less-systematic way of taking cities by
disuasing players.

Anyway, what becomes the gold depends on the logic of city-bribing: on who
acts in such an action and on what applies diplchance (equivalent to
"when" diplchance is applied).

1/ on what applies diplchance: 

- reachability of the actor: actor's final decision and act is 100%
reliable once the cost has been paid (in this case gold should be kept
by the attacker if bribe fails)

- final decision of the actor: once the cost has been paid, the actor
can change sides (in this case, what becomes gold depends on the actor)
or is caught

2/ who are actors: 

- local government who act for/against its nation (in this case gold
should go to the attacked nation it bribe fails), 

- local armed people (kind of mercenaries) who take the city by force
and from the inside (in this case gold is lost for everyone if bribe
fails).

3/ proposition about what becomes gold of the unlucky attacker:

A 3 values "bribegold" option which can reflect those cases:

1 gold is kept by the attacker
  -> diplchance applies on reachability
2 gold goes to attacked nation (with application of corruption rate); 
  -> diplchance applies on final act, actor is/are (a) public person(s)
3 gold is lost for everyone; 
  -> diplchance applies on final act, actor are local armed people

Another option could be dependant on the form of government of the
attacked nation (not my prefered one).

--
G. Gracian