I've found a simple solution to the certainty of goblin world domination: The 40.xx goblins have no religion other than the slade tower clown who drives them, so my thought was that goblins were the nearest cavern race to the slade tower that could provide a slave population for the demon. But what about the other cavern races? The olm-men, the reptile-men, the ant-people and the cave-swallow men, (ect...)? I just take all of the cavern races in the "entity_default" file and add them to the "ENTITY:EVIL" race description
[ENTITY:EVIL]
[CREATURE:GOBLIN]
[CREATURE:AMPHIBIAN_MAN]
[CREATURE:REPTILE_MAN]
[CREATURE:SERPENT_MAN]
[CREATURE:RODENT MAN]
[CREATURE:BAT_MAN]
[CREATURE:ANT_MAN]
[CREATURE:OLM_MAN]
[CREATURE:CAVE_SWALLOW_MAN]
[CREATURE:CAVE_FISH_MAN]
[TRANSLATION:GOBLIN]
[DIGGER:ITEM_WEAPON_PICK]
(ect...)
then also add the "Goblin" race to the "ENTITY:SUBTERRANEAN_ANIMAL_PEOPLES" description.
Now we have Cave-swallow men civs attacking amphibian-man evil civs and goblin civs attacking both of those as well. The Slade-tower Clowns now compete with each-other as well as the rest of the world, which thins out their numbers quite a bit and the ages reflect the race numbers a bit better.
However, post-world gen sieges happening off-screen are rather disappointing in that they don't use the same basic engine as the one used for game gen history mode calculations. An "army on the move" could so easily be an encounter following a set path from A to B once the "invasion" event is generated, with tiles per day set up as the speed of the slowest unit and then just scheduling each further step completed as a calendar scheduling function. I mean, we could assume that such and such an army invades such and such a place, then calculate the travel time of the slowest unit in the army for this event and schedule it to happen that many seasons forward. Adventure mode could use a probability chart based on the ration between an adventurer's "sneak" skill and the individual with the highest "observation" skill (or an average of those skill levels) as the chance that they could sneak through the army in Quick-travel mode. Otherwise, the character (and companions) are discovered and an encounter is called with the surrounding eight squares plus the encounter square, that contain an "army". Each square contains a squad of soldiers or a supply wagon or whatever, (btw: none of those wagons will move while fighting is going on, so we don't have to worry about those - they're just window dressing.) By thinning out the actual numbers of an army, the adventurers and companions can decrease the strength of the attacking force or demoralize them. This whole "forever sleeping in a tent" and therefore easily murdered thing is pretty bogus.