some ideas around fortifications which i might propose for the next congress if they aren't shot down immediately ...
1. the big one first: forts and citadels only deal adjacent damage when occupied by a unit
No. The Citadel is a conditional, static form of the Great General.
GG is able to travel and strengthen units with his aura anywhere on the map. Plus his aura can be expanded and strengthened through the policy tree.
The citadel is unable to move and the resource income from it is relatively small until the late game. Something like 12 income by turn 300, but Holy Site is capable of producing 20-25 income at the same time. Sawmills 15-18. Hills 14-16.
That is, without a protective aura, the Citadel will be a rather weak tile.
2. when a unit in a fortification is destroyed, the fortification is automatically pillaged (no pillage bonuses for the killing unit though)
No. Restoring the Citadel takes 3-4 turns. Repairing something in 3-4 turns during a massive invasion is very difficult and the AI is unlikely to do this, since it likes to run away with its workers to the city (although the AI repairs it in 1 turn). This will mean that the front has collapsed and enemy units will simply enter the city territory and block all the tiles, which will instantly paralyze production.
3. forts get adjacent damage -10 (when occupied by a unit!)
opinions?
No. This will be analogous to a mini-Citadel. If you install a Citadel, you can create 3 forts around it. You will get an incredibly huge protective aura.
-30 in the 1st radius from the Citadel and -10 in the 2nd radius.
The forts are already quite good, although I think they need to increase their defense a little. 50% does not provide sufficient protection for a unit against a massive attack.
The advantage of a fort is that the unit does not leave the fort when attacking - that is, it does not need to spend 1+ movement point to return to the same tile. You can come running with cavalry, strike and run to the rear, placing an infantry in the fort. Although this feature is also a disadvantage if the unit has a promotion with 10 damage to all adjacent enemies when killed and moved to the captured tile, since the movement does not occur and the effect does not work.
But Citadels are of course a huge problem for the AI, as it doesn't find ways to deal with them effectively.
The AI is not afraid to attack units with a melee attack if it takes 30 damage, but for some reason avoids leaving a unit in the Citadel aura for 1 turn if it is not able to immediately occupy the Citadel tile.
Perhaps the reason is that the AI assesses the damage for each specific unit and the risk becomes unacceptable. If the damage for the entire attacking group had been assessed, the situation would have been different. For example, 3 infantry in the Citadel aura will receive 90 damage, but this will allow the next turn to kill the defender with artillery support and advance to the Citadel with cavalry/commandos, while simultaneously looting it. Or put 4 attacking infantry with almost full health in the Citadel, blocking the recapture, and destroy it on the next turn. Here it turns out that a total of 3+ units with 300+ health are involved and the defender will have to generate 300+ (-90 thanks to damage through the Citadel's aura) damage in one turn to kill them all. It can be difficult for a defender to generate the required amount of damage, especially in different tiles, since the distances for attacks are limited.