New update:
- opened conditions to free occupied slots
- revealed owner of tiles is reset when a civilization collapses or is assigned to a slot
- fixed canEverRespawn
- corrected conditions for outdated civilizations
In combination these commits address some issues with certain civilizations not spawning. As you know, there is a limited number of available slots and it's possible that all of them are occupied when a new civilization is about to spawn. The most critical period of the game for this is around 1000-1200 where a lot of civilizations spawn within short sequence of each other while older civilizations are potentially still alive. Normally, what was supposed to happen is that in such a situation the game makes a collapsing or outdated civilization collapse to make room for a new one.
There were several issues with this. The most important aspect where the displayed owner of a tile that had been revealed in the past but it not currently under vision. I had originally prevented the slots of any such players from being reused because it would change the colour of these formerly revealed territories. This "wasted" a lot of otherwise usable slots already. Furthermore, when a civilization is collapsed to make room for a new one, their former territory is likely to have been within their vision so their colour is still on the map, and the slot could not be reused.
To solve this, instead I made the revealed culture of collapsed civilizations reset to Independents. This opened more slots to be assigned and made the process of opening more slots if needed function as intended.
I also made the rules about which civs can be collapsed to open a slot a bit more permissible. In the process, I also fixed two bugs. The condition for whether a civilization can ever respawn was flipped, and some civilizations where considered outdated when they weren't actually. Both of these conditions figured into whether a civilization was eligible to be collapsed to open a slot.
All of these changes taken together should make it a lot less likely that a civilization cannot be spawned because of a lack of slots.