@ Koshling:
Here is a Max Comp game: Its weird, i take over the enemies fort, and it becomes mine, BUT then the next turn, even if i am on that tile, its back to being the enemies?
EDIT: Also below, i really need this one solved, i have two different modcomps going on, and if they work, i can add them C2C? Thats why the file is marked "Caveman2Cosmos - Copy"
http://forums.civfanatics.com/showpost.php?p=10778508&postcount=3689
The fort issues are down to inconsistencies in how cultural ownership works.
Right now when you move inot a fort (as long as it's not a hidden nationality unit in my version, which will be pushed later today) you gain ownership of the fort tile + all surrounding tiles which are not within 1 tile of their current owner's city or another fort.
However, at the start of each turn cultural ownership is re-evaluated, and the person with the highest culture in a tile gets ownership provided that they have a city within cultural influence range of it (which varies with the city's cultural development and is its border rnage in the absence of other culture). This calculation does not apply to city plots. However, it DOES apply to fort plots, so the fort is taken back along with its surrounding tiles!
I am changing things as follows:
1) The surrounding tiles will only change ownership when you capture a fort if YOUR culture is the culturally dominant one there (i.e. - the captured fort serves to provide a cultural influence of range 1). In your game this means no adjacent tiles will change ownership. However, in a contested border area against an opponent with fixed borders it would tend to capture tiles back towards your borders.
2) The cultural ownership calculation will no longer apply to tiles occupied by forts provided there is at least one of the owner's units there. This means you'll keep your captured fort(s) so long as you don't vacate them totally.
In regard to your second save game that you report as CTDing, it does not do so for me (with my earlier fixes I have posted about previosuly today). So it's either the same issue as one of the other 2 CTDs I have fixed today, or it needs your experimental extra assets to reproduce it. Once I upload a patch (in the next hour) try that and let me know if it cures it.
Edit - I'm going to have to fairly urgently change the AI to make sure it doesn't leave unguarded forts now, or they become a massive achilles heal. Will do that next week.