Way to increase AI settler range? / Making the Terra map work

[Trigan Emperor]

I've tried a few times now to get a good exploration and colonization game going with the Terra map script, which starts all the Civs in an Old World with an uninhabited New World in which to seek adventure..

These games don't turn out as hoped as the AI civs are rather uninterested in establishing New World colonies until quite late in the game, by which time it's too late for them to be of much consequence.

My most recent attempt to play this game was with 22 civs on a Standard map size. With civs only able to found a couple of cities in the Old World due to overcrowding, I'd hoped that they would be more likely to found New World cities. I also gave a big boost to the AI Expansion Flavor:

UPDATE [Leader_Flavors] SET [Flavor] = [Flavor] + 5 WHERE [FlavorType] = 'FLAVOR_EXPANSION';

This code did certainly seem to make the AI civs found more cities in the Old World, and were even settling one-hex islands with a single fish resource, which they don't normally do. Unfortunately, they were still very slow to colonize the New World.

So I figured that something else would need to be tweaked to get a Terra map game to work and had a look through the GlobalDefines.XML file (BNW). There were a couple of data values that looked interesting:

        <Row Name="SETTLER_EVALUATION_DISTANCE">
            <Value>24</Value>
        </Row>
        <Row Name="SETTLER_DISTANCE_DROPOFF_MODIFIER">
            <Value>67</Value>

So I had a google, and came up with some interesting stuff from other threads. From this thread:

Anyway, the ones that are supposed to make the difference to very-long-range settling (changed because people complained about it) are, I believe, SETTLER_EVALUATION_DISTANCE (current default 20) and SETTLER_DISTANCE_DROPOFF_MODIFIER (current default 75), which I believe give an absolute cap on the locations considered, and devalue more distant sites, respectively.

And from this thread, discussing an earlier Civ V version change:

Hm? The 'evaluation distance' went from 40 to 12 so it doesn't look out nearly as far. Also the 'dropoff modifier' increased to 99, which means that as you get further away, the weighting gets less. This should make the AI's build more 'compact' empires, and not settle 30 tiles away, right next to you for no reason.

And these changes made:

changes from 1.0.0.20 to 1.0.0.62

SETTLER_EVALUATION_DISTANCE changed from 40 to 12
SETTLER_DISTANCE_DROPOFF_MODIFIER changed from 85 to 99

So these look promising, but I'm not quite sure how they work.

i) SETTLER_EVALUATION_DISTANCE

Is this the maximum distance away from a city that an AI settler will found a city? So the current value of 24 in the GlobalDefines.XML file means that an AI settler will found a city no more than 24 hexes from one of their cities?

ii) SETTLER_DISTANCE_DROPOFF_MODIFIER

From one of the threads linked to above:

Did you consider increasing "SETTLER_DISTANCE_DROPOFF_MODIFIER"?

It may be a percentile multiplier that devalues further hexes. It may work that a hex 1 away is 100, 2 is 75, 3 is 56.25, 4 is 42.2...etc. I haven't tested any of this out, but it may be a possibility.

I haven't found any confirmation of this, but it looks like a reasonable conjecture. Anyone know? In this case, a lower number would produce a more clustered arrangement of cities, I presume.

-------------------

So, in conclusion, if this is all correct, then the things to change for a Terra map game might be:

a) SETTLER_EVALUATION_DISTANCE

I'll have to open a game and check exactly what distance would be suitable, but if it's currently set at 24, then this value could probably be at least doubled.

b) SETTLER_DISTANCE_DROPOFF_MODIFIER

This one's a bit more tricky. It's currently set at 67. Perhaps this should be increased a bit, although I'm not certain.

Any thoughts?

 

[Trigan Emperor]

I've tried running a test game as an observer with these settings:

        <Row Name="SETTLER_EVALUATION_DISTANCE">
            <Value>72</Value>
        </Row>
        <Row Name="SETTLER_DISTANCE_DROPOFF_MODIFIER">
            <Value>90</Value>
        </Row>

It's 1800 and there's a couple of tiny AI settlements in the New World. So no real change. With the map unhidden, I can see half a dozen barbarian-captured settlers there, so that's one issue.

The next thing to try will be raising the SETTLER_DISTANCE_DROPOFF_MODIFIER all the way, probably to 99. And if that doesn't work, then lowering it. So trial and error.

 

[SLGray]

Have you read this topic: https://forums.civfanatics.com/threads/ai-city-distance.408506/

 

[Trigan Emperor]

Have you read this topic: https://forums.civfanatics.com/threads/ai-city-distance.408506/

Yes, thanks. I linked to it in the opening post.

I've done three test games now, all with SETTLER_EVALUATION_DISTANCE set at 72 (default: 24), and with three different SETTLER_DISTANCE_DROPOFF_MODIFIER settings: 1, 90, 99 (default: 67).

I've not really noticed any significant difference betweem them, to be honest, or with the default settings. In the 99 Modifier setting, Polynesia had seven New World cities by 1750, but they have ocean-going ability from the game's start, and there was no great difference regarding other civilizations.

As I mentioned before, there were several captured settlers, as the AI doesn't seem to do a good job at protecting them. One could turn off barbarians, I suppose, but part of the fun of a New World game is that there's some danger amid the exploration. I was wondering if perhaps there are any barbarian behavior settings, such as making them ignore or not capture civilian units like settlers and workers.

Otherwise, I'm not sure if there's any further progress to be made to get this game format to work. I might try one final test with very high values, perhaps 100 for SETTLER_EVALUATION_DISTANCE and 200 for SETTLER_DISTANCE_DROPOFF_MODIFIER.

I should also add that these test games have been played with +3 for FLAVOR_EXPANSION, so they have a boost in that area.

UPDATE [Leader_Flavors] SET [Flavor] = [Flavor] + 3 WHERE [FlavorType] = 'FLAVOR_EXPANSION';

There are some other things that might work with some tinkering, but I'm not sure what they do:

AI_STRATEGY_AREA_IS_FULL_PERCENT
AI_STRATEGY_MINIMUM_SETTLE_FERTILITY
AI_STRATEGY_EARLY_EXPANSION_NUM_CITIES_LIMIT
AI_STRATEGY_EARLY_EXPANSION_NUM_UNOWNED_TILES_REQUIRED
FLAVOR_EXPANDGROW_COEFFICIENT
ECONOMICAISTRATEGY_EARLY_EXPANSION

 

[Trigan Emperor]

One possible issue I noticed when resuming the game as a player after Autoplaying it, is that even in the Industrial Era, the AI hadn't mapped out much of the world, including the New World. So perhaps the issue could be that the AI aren't sending settlers to the New World because they can't see it?

Some ideas to get around this might be:

- Modify AI behavior to make it explore more?
- Increase Recon Flavor, I presume making AI build more recon units.
- Allow ships to cross ocean tiles from the start of the game, but not embarked land units, so the AI should hopefully have some mapping of the New World done before being able to send settlers.
- Reveal the whole map to the AI players, but not human.

Is there a way to play the game with the map revealed to all players at the start? If so, it would be interesting to Autoplay it and see if it makes any difference.

 

[Trigan Emperor]

I did a final test with SETTLER_EVALUATION_DISTANCE set at 100 and SETTLER_DISTANCE_DROPOFF_MODIFIER at 200, but there was no significant difference.

I also took control over one AI player in the medieval era and, using the In-Game Editor, built and then deleted some units to reveal part of the New World, along with a sea passage to get there. I then let it Autoplay some more and no settlers were sent by the AI ruler..

So unless anyone else has any other ideas, then I think this project is dead.