I posted this in territory and diplomacy but it makes more sense
here (repost)
Basically another idea for Forts would be grab unclaimed territory.
Forts and Units as culture sources
I kind of like this idea now, since it gives a another reason to build forts. I also like how this could tweak the 'borders' with either limited warfare (no city conquest), and to claim culture without building cities.
1. Units claiming culture tiles
Units can optionally wage war on the local 'country folk' of a tile to either 'pillage' their culture, or to claim their allegiance (each would be a separate act). This would be as an actual battle, with a chance of losing the unit or hitpoints, but no chance of being promoted, and it would potentially be 'disreputable'. An already cultured territory could be pillaged by one tile, as long as it wasn't actually within the economic zone of some city, and wasn't a 'swiss-cheese' hole (meaning you can't pillage holes into the territory----you can only pillage from edges).
An 'uncultured' territory could separately be attacked and claimed, but the addition would have to be contiguous to one of that Civ's existing cultural territory(ies), and within the economic zone of a city. This would be like 'warrior-rushing' culture.
By allowing units interact with culture, way, the national borders then interact with the Civs cultural projection more finely, since the military units can shape the borders in war, without dealing with klunky cities. It'd also better the game since city-abuse (building cities to claim cultural territory) wouldn't be as necessary, at least if war is an option, and the overall city count could be lower (speeding up the turns).
2. Forts claiming culture tiles
Once manned, Forts 'domesticate' uncultured land, generating allegiance when no cities are present. Forts can't really compete versus a city with real culture (i.e. city improvements), but they'd be about equal in cultural strength, to a city with no improvements for culture purposes, except they would't project culture as far---perhaps only into the tile they're in.
Alternatively,
a string of forts could also be used to claim the culture of a string of road or river tiles (rivers will supposedly double as road in CIV4). The length of a road/river between two forts could automatically be claimed, for some length (I dunno, maybe 5 tiles). A stipulation would probably be that the forts be held by units of the same culture, and the cultural control would be lost as soon as that was no longer true. Also, the culture generated this way would be weaker than that generate by cities/current cultural projection.
With this, colonies/cities wouldn't be necessary in some cases to import resources, and it'd simulate a Great Wall/Hadrian's wall better than that Wonder.
Alternatively, using the units-claiming-cultural-tiles idea above, then if you had fort, it'd be grounds for a unit to culturally subjugate the adjacent tiles (in the manner of the first idea), to some diameter, maybe that equal to a city. That subjugation would still be challengeable, though, by like means by other Civs (Cultural tiles within a city's zone would be impervious to culture pillaging, but not so if the tiles were claimed by virtue of a fort).
AND Alternatively, using the units-claiming-cultural areas (or in addition to it) and the string of forts, the string of forts could delineate an area that your civ claims, but hasn't settled. Once you've used a string of forts to enclose an area of 'uncultured' tiles contiguous to your civ's normal city/cultural projection, then units could be used to culturally attack the tiles (as above) in your favor.
Thoughts?
With the combination of those ideas it'd be possible to civ a civ that was very hegemonious (like the real Romans), using forts and violence, without settling cities. This would be great for a Domination victory scenario
But then there needs to be the possibility that cultured tiles far from cities can spontaneously revolt without being flipped by another civ, and also possibly some kind of happiness calc for those tiles to determine revolt possibiliities. Putting down such a revolt would simply be a matter of re-conquering tiles.
Such a tile happiness calc would be the natural limit on the ability to project culture with war, but without cities. It would actually probably be quite limited, being dependent upon distance to the nearest city, and probably require a road path to said city.
Also, the idea that ALL 'uncultured' tiles are always populated, though they produce barbarians, is probably false. The first idea of conquering 'uncultured' tiles by unit would probably have to be limited to river valleys, bonus food tiles, and the areas within a cities hypothetical economic zone, since some 'uncultured' tiles probably are just rocks.
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