Open Borders - is it worth it or not ?

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Camillo

Chieftain
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Witajcie.

I have a few questions about Open Borders agreements.
So far I always made Open Borders agreements to all AI that wanted to.
But what if you would always refuse for Open Borders ?

1. Would AI be more aggressive because of refusing Open Borders ?
2. Would it harm your relations to AI because of refusing Open Borders ?
3. Is it possible to have friends without Open Borders ?
4. Is it possible to make defensive pacts without Open Borders ?
5. Is it possible to have trade routes without Open Borders ?
6. What is real practical advantage of having Open Borders except obvious possibility to cross AI territory ?
 
Camillo said:
Witajcie.

I have a few questions about Open Borders agreements.
So far I always made Open Borders agreements to all AI that wanted to.
But what if you would always refuse for Open Borders ?

1. Would AI be more aggressive because of refusing Open Borders ?
2. Would it harm your relations to AI because of refusing Open Borders ?
3. Is it possible to have friends without Open Borders ?
4. Is it possible to make defensive pacts without Open Borders ?
5. Is it possible to have trade routes without Open Borders ?
6. What is real practical advantage of having Open Borders except obvious possibility to cross AI territory ?
Click to expand...
Open borders increases the amount of tourism output one civ has on the other (though I forget which way it goes right now).

You generally don't take a diplomatic hit from refusing open borders, but the AI will often have that as a "stepping stone" toward a declaration of friendship and may not make that offer if you don't have open borders. So refusing won't hurt your diplomacy, but it might hamper it from moving forward.

I'll often share open borders with a civ that's close by, but if it's someone on the other side of the map and I don't have units to spare exploring their territory, I'll just offer them my open borders for +1 GPT.
 
If you are playing a game with no focus on tourism, then closing your own borders slows the AI's tourism gains against you. This is particularly important with the civs on your own continent. (The inverse is naturally also true.) But it doesn't make much of a difference in the early game, which is when you are forming your first relationships.
 
I almost never open my borders. Opening your borders has a bunch of negative effects:

*Their tourism affects you more.

*The AI tends to clog up your road system with scouts, religious units, and even entire armies if they're trying to invade someone behind you. This isn't too much of a problem for your military units, but it's a serious pain in the butt for your workers, settlers, and religious units: none of them can pass through AI units. Besides, sometimes the AI will park itself on the exact tile that you want to improve/dig/whatever.

*Having open borders makes you more susceptible to enemy religious spread. Missionaries passing through closed borders take damage, so the AI never uses them to proselytze your lands when your borders are closed. Prophets don't take damage, but nevertheless the AI usually don't use prophets on you when your borders are closed.


What's more, there's pretty much no upside to opening your borders. Keeping your borders closed might slightly ding your diplomacy, but not much.

So... yeah. Just buy Open Borders from the AI with gold or gold per turn.
 
Plumfairy said:
Besides, sometimes the AI will park itself on the exact tile that you want to improve/dig/whatever.

.
Click to expand...

Lost count of the amount of times this has happened - far too often to be coincidental.
 
on Tourism, there's no issue with having OB w/an AI unless they are a real Tourism Monster + you don't have much of anything goin on w/Tourism.

i've been wondering if not having OB with an AI that you can sign an RA with might lower the gold/resource part of a RA deal (because they will put OB on the RA table). it might do just that but haven't paid enough attention.

last case: i will give OB to civ who needs to cross my territory to smash a neighbor's face. as long as i have a semi-decent home defense this does not make me too nervous, and besides what's not to like by facilitating one AI attacking another? (unless it's a runaway that needs my lands to cross, ofc)

oh right, if i do have decent Tourism, i like OB for my own bonus to Tourism vs. the other AI.
 
Plumfairy said:
I almost never open my borders. Opening your borders has a bunch of negative effects:

*Their tourism affects you more.

*The AI tends to clog up your road system with scouts, religious units, and even entire armies if they're trying to invade someone behind you. This isn't too much of a problem for your military units, but it's a serious pain in the butt for your workers, settlers, and religious units: none of them can pass through AI units. Besides, sometimes the AI will park itself on the exact tile that you want to improve/dig/whatever.

*Having open borders makes you more susceptible to enemy religious spread. Missionaries passing through closed borders take damage, so the AI never uses them to proselytze your lands when your borders are closed. Prophets don't take damage, but nevertheless the AI usually don't use prophets on you when your borders are closed.


What's more, there's pretty much no upside to opening your borders. Keeping your borders closed might slightly ding your diplomacy, but not much.

So... yeah. Just buy Open Borders from the AI with gold or gold per turn.
Click to expand...

Plus if they want to backstab you and declare war their units are in your territory ready to go. It's been a long long time since I've given open borders to the AI, but I don't think their units move to your borders if they declare.
 
Beaver79 said:
Plus if they want to backstab you and declare war their units are in your territory ready to go. It's been a long long time since I've given open borders to the AI, but I don't think their units move to your borders if they declare.
Click to expand...

Yes they do. Upon declaration, all units are forced out. Declaring while your units are actually within the enemy's borders is a very bad idea, since you don't have a lot of control over where they start.
 
Polisurgist said:
Yes they do. Upon declaration, all units are forced out. Declaring while your units are actually within the enemy's borders is a very bad idea, since you don't have a lot of control over where they start.
Click to expand...

That's why you put a wall of units on their border and steamroll through :D
 
i've been wondering if not having OB with an AI that you can sign an RA with might lower the gold/resource part of a RA deal (because they will put OB on the RA table). it might do just that but haven't paid enough attention.
Click to expand...

It depends. Sometimes they begin by putting OB on the table, but if you remove it from the deal they will accept it as is.

At other times, they ask for a bit more gold if you remove OB from the table.

It varies according to AI and how you stand diplomatically.

But they don't value OB much anyway. Most AI will sell it to you for 1 or 2 gpt, and others for half that (they ask 1 gpt but give back about half the total amount in gold). The AI offering 24 or 50 gold + OB for 1 gpt is typical in Marathon late games.

So it doesn't lower the price of deals by much.
 
Good to hear open borders are not essential for diplomacy. In Civ4 it did matter if I remember well. But in Civ5 having open borders is really annoying, because AI is flooding your territory with units, grabbing up space for your workers and units moving (due to 1 unit per tile system), so I would not open borders for AI anymore since now. Thanks.
 
Camillo said:
1. Would AI be more aggressive because of refusing Open Borders ?
2. Would it harm your relations to AI because of refusing Open Borders ?
Click to expand...

In my experience one time in which it can be dangerous to refuse open border is when you're weak and stand between two AI with a bad relationship.

It might be a coincidence, and almost certainly the friendly AI would have turned against you eventually, but I've had a few games in which I refused passage across my territory to a friendly AI that had clearly prepared to attack the AI on the other side of me. The DoW came not much longer after that.

It can also come this way: AI 1 asks you to go to war against AI 2. You refuse. A few turns later AI 1 asks for OB. You refuse. The "friendly" AI 1 ends up denouncing you and/or using its army against you instead and you get something like "your weakness is my opportunity". Bribing AI 1 so they attack AI 2 can buy some time, but if they can't reach AI 2 without OB with you, the "white war" only delays the DoW on you.

Another situation where I've seen the AI possibly pissed off about a refusal to give OB is when they try to connect two cities and must use the roads on your territory to complete the connection. I've been DoW in situations like this, but there were already border tensions and it's hard to tell if the refusal to give OB played any role.

Otherwise I frequently (in fact most often) refuse OB to the AI without seemingly any consequence (they often offer a DoF or agree to renew one despite that. As OB is a kind of stepping stone on the way to DoF, I guess it might delay a DoF from coming, waiting for another positive diplo modifier to replace that, like having traded, or sending TR).

Apparently the patch was supposed to make the AI more cautious about selling open borders to players with high tourism, but I haven't seen must results from that in my post patch games so far. They seem as happy as before to sell you a Cultural Victory for 1 gpt while you block theirs.

On some maps it can be highly beneficial to refuse OB but buy them from the AI. Before Astronomy on water maps this can block the AI from exploring parts or even whole areas of the map. That can be useful if you intend to wipe a nearby civ before the others discover its existence, or to increase your chance to be the one able to found the WC.

Is it possible to have trade routes without Open Borders ?
Click to expand...

TR ignore borders. Personally I'd like them to split "Open Borders" into more specific agreements: one would allowing a foreign trade concession in your territory, allowing trade routes between two civs. A second type of agreement would allow religious units access to your territory (you could thus incite a civ to send you a GP or missionaries by giving it to them). Another would allow workers and scouts passage. The final type would allow military units the right to cross or use your territory, including stationing an aircraft in your cities. It would give a diplo hit with your neighbor that gets attacked because of that. I would also give the possibility to disregard closed borders, with attrition for the units entering borders without permission, and a diplo hit increasing every turns this lasts, leading to denouncement and possibly war.
 
Plumfairy said:
*Having open borders makes you more susceptible to enemy religious spread. Missionaries passing through closed borders take damage, so the AI never uses them to proselytze your lands when your borders are closed. Prophets don't take damage, but nevertheless the AI usually don't use prophets on you when your borders are closed.
Click to expand...

This may be slightly off topic, but I've noticed that when I found a religion and stationed an Inquisitor next to my capitol, the AI doesn't try to convert ANY of my cities, Open Borders or not. I've been playing on Emporer level. This has been the case each of my last two games. Have I just been getting lucky? Or does the AI think something like, "Well since I can't get the capitol, I won't even try any of his other cities."

Thoughts?
 
Polisurgist said:
Yes they do. Upon declaration, all units are forced out. Declaring while your units are actually within the enemy's borders is a very bad idea, since you don't have a lot of control over where they start.
Click to expand...

And IRRC the same happens to your units if they are in someone's territory and that someone declares war on you.
 
EK834 said:
And IRRC the same happens to your units if they are in someone's territory and that someone declares war on you.
Click to expand...

Yeah, the Open Borders agreement, along with all other deals, become null and void first, so you're forced out.
 
Polisurgist said:
Yes they do. Upon declaration, all units are forced out. Declaring while your units are actually within the enemy's borders is a very bad idea, since you don't have a lot of control over where they start.
Click to expand...

Although you don't have much control over where they start, it's usually not too hard to figure out; they're placed in the nearest unoccupied neutral tile. Figuring out where they're going to appear only gets tricky when your units are in the middle of his territory & equidistant from multiple borders.
 
Polisurgist said:
Yeah, the Open Borders agreement, along with all other deals, become null and void first, so you're forced out.
Click to expand...

Ever since I knew this function in civ 5, I knew civ 5 was far better than civ 4, which had the exact opposite! Cancelled border agreement didn't push the soldiers out on declaration of war in civ 4.

1. Would AI be more aggressive because of refusing Open Borders ?
2. Would it harm your relations to AI because of refusing Open Borders ?
3. Is it possible to have friends without Open Borders ?
4. Is it possible to make defensive pacts without Open Borders ?
5. Is it possible to have trade routes without Open Borders ?
6. What is real practical advantage of having Open Borders except obvious possibility to cross AI territory ?
Click to expand...

1. No, but they might keep asking in the future.
2. Nope.
3. Yes. Open borders isn't needed to secure friendship but it helps.
4. I may forgotten the answer here, but concerning defensive pacts, do not use them. They are not very reliable.
5. Yes. Although I think open borders should increase the amount of gpt from trade routes with civs from open borders. Then open borders is seen as a free trade agreement.
6. Just tourism. Grab the 5th policy from aestethics, send a trade route to someone with open borders and you will have an 80% tourism bonus over them. :)

I have had one case where one of my allies was blocking my way to a science victory and I had to DoW my ally to remove the unit out of the way. My feelings from that event:
- "Yes, got the last part and I have enough moves to get to capitol in time"
- "No! Dam Siamese Sam is blocking the road. I won't make it in time. Greece will win science victory!" >Nearly moves the spaceship part off the road<
- "...oh wait, derp, I can just DoW Siam to move the unit. Problem solved. Yes, won science victory on emperor from behind!"
 
Also, Open Borders makes you more open and vulnerable to espionage. If you have only an embassy, you only need to put a defensive spy in your capitol. If enemies are aware of your other cities, they can steal from any of your cities.
 
Looking inside the code (CivDiplomacyAI.cpp and CivDealAI.cpp), there is nothing that "transforms" OB deals or rejections into any sort of diplomatic repercussion/consequence/bonus... So, accepting or rejecting OB proposals, or generating them, does not add or remove any penalty/bonus to diplo stances whatsoever. The only consequences of OB deals are the ones that can be related to the gameplay itself: allowing another civ to scout, or to pass en route to attack another one, or the effects related to tourism.

On the other hand, there is extensive code to check and, more importantly, to valuate OB deals as related to the game scenario and environment: DoFs make OBs more likely, while opposite stances or approaches do, well, the opposite. AI also checks in detail if the potential OB partner is going for CV, and also other details such as Military strength, the approach and opinion towards said civ, etc etc.
 
EK834 said:
Apparently the patch was supposed to make the AI more cautious about selling open borders to players with high tourism, but I haven't seen must results from that in my post patch games so far. They seem as happy as before to sell you a Cultural Victory for 1 gpt while you block theirs.
Click to expand...

See below (especially where comment mentions CV): ;)

Code: 
/// How much in V-POINTS (aka value) is Open Borders worth?  You gotta admit that V-POINTS sound pretty cool though
int CvDealAI::GetOpenBordersValue(bool bFromMe, PlayerTypes eOtherPlayer, bool bUseEvenValue)
{
	CvAssertMsg(GetPlayer()->GetID() != eOtherPlayer, "DEAL_AI: Trying to check value of Open Borders with oneself.  Please send Jon this with your last 5 autosaves and what changelist # you're playing.");

	MajorCivApproachTypes eApproach = GetPlayer()->GetDiplomacyAI()->GetMajorCivApproach(eOtherPlayer, /*bHideTrueFeelings*/ true);

	// If we're friends, then OB is always equally valuable to both parties
	if(eApproach == MAJOR_CIV_APPROACH_FRIENDLY)
		return 50;

	int iItemValue = 0;

	// Me giving Open Borders to the other guy
	if(bFromMe)
	{
		// Approach is important
		switch(eApproach)
		{
		case MAJOR_CIV_APPROACH_HOSTILE:
			iItemValue = 1000;
			break;
		case MAJOR_CIV_APPROACH_GUARDED:
			iItemValue = 100;
			break;
		case MAJOR_CIV_APPROACH_AFRAID:
			iItemValue = 20;
			break;
		case MAJOR_CIV_APPROACH_FRIENDLY:
			iItemValue = 50;
			break;
		case MAJOR_CIV_APPROACH_NEUTRAL:
			iItemValue = 75;
			break;
		default:
			CvAssertMsg(false, "DEAL_AI: AI player has no valid Approach for Open Borders valuation.  Please send Jon this with your last 5 autosaves and what changelist # you're playing.")
			iItemValue = 100;
			break;
		}

		// Opinion also matters
		switch(GetPlayer()->GetDiplomacyAI()->GetMajorCivOpinion(eOtherPlayer))
		{
		case MAJOR_CIV_OPINION_ALLY:
			iItemValue = 0;
			break;
		case MAJOR_CIV_OPINION_FRIEND:
			iItemValue *= 35;
			iItemValue /= 100;
			break;
		case MAJOR_CIV_OPINION_FAVORABLE:
			iItemValue *= 70;
			iItemValue /= 100;
			break;
		case MAJOR_CIV_OPINION_NEUTRAL:
			break;
		case MAJOR_CIV_OPINION_COMPETITOR:
			iItemValue *= 150;
			iItemValue /= 100;
			break;
		case MAJOR_CIV_OPINION_ENEMY:
			iItemValue *= 400;
			iItemValue /= 100;
			break;
		case MAJOR_CIV_OPINION_UNFORGIVABLE:
			iItemValue = 10000;
			break;
		default:
			CvAssertMsg(false, "DEAL_AI: AI player has no valid Opinion for Open Borders valuation.  Please send Jon this with your last 5 autosaves and what changelist # you're playing.")
			break;
		}

		// If they're at war with our enemies then we're more likely to give them OB
		int iNumEnemiesAtWarWith = GetPlayer()->GetDiplomacyAI()->GetNumOurEnemiesPlayerAtWarWith(eOtherPlayer);
		if(iNumEnemiesAtWarWith >= 2)
		{
			iItemValue *= 10;
			iItemValue /= 100;
		}
		else if(iNumEnemiesAtWarWith == 1)
		{
			iItemValue *= 25;
			iItemValue /= 100;
		}

		// Do we think he's going for culture victory?
		AIGrandStrategyTypes eCultureStrategy = (AIGrandStrategyTypes) GC.getInfoTypeForString("AIGRANDSTRATEGY_CULTURE");
		if (eCultureStrategy != NO_AIGRANDSTRATEGY && GetPlayer()->GetGrandStrategyAI()->GetGuessOtherPlayerActiveGrandStrategy(eOtherPlayer) == eCultureStrategy)
		{
			CvPlayer &kOtherPlayer = GET_PLAYER(eOtherPlayer);

			// If he has tourism and he's not influential on us yet, resist!
			if (kOtherPlayer.GetCulture()->GetTourism() > 0 && kOtherPlayer.GetCulture()->GetInfluenceOn(GetPlayer()->GetID()) < INFLUENCE_LEVEL_INFLUENTIAL)
			{
				iItemValue *= 500;
				iItemValue /= 100;
			}
		}
	}
	// Other guy giving me Open Borders
	else
	{
		// Proximity is very important
		switch(GetPlayer()->GetProximityToPlayer(eOtherPlayer))
		{
		case PLAYER_PROXIMITY_DISTANT:
			iItemValue = 5;
			break;
		case PLAYER_PROXIMITY_FAR:
			iItemValue = 10;
			break;
		case PLAYER_PROXIMITY_CLOSE:
			iItemValue = 15;
			break;
		case PLAYER_PROXIMITY_NEIGHBORS:
			iItemValue = 30;
			break;
		default:
			CvAssertMsg(false, "DEAL_AI: AI player has no valid Proximity for Open Borders valuation.  Please send Jon this with your last 5 autosaves and what changelist # you're playing.")
			iItemValue = 0;
			break;
		}

		// Reduce value by half if the other guy only has a single City
		if(GET_PLAYER(eOtherPlayer).getNumCities() == 1)
		{
			iItemValue *= 50;
			iItemValue /= 100;
		}

		// Boost value greatly if we are going for a culture win
		// If going for culture win always want open borders against civs we need influence on
		AIGrandStrategyTypes eCultureStrategy = (AIGrandStrategyTypes) GC.getInfoTypeForString("AIGRANDSTRATEGY_CULTURE");
		if (eCultureStrategy != NO_AIGRANDSTRATEGY && GetPlayer()->GetGrandStrategyAI()->GetActiveGrandStrategy() == eCultureStrategy && GetPlayer()->GetCulture()->GetTourism() > 0 )
		{
			// The civ we need influence on the most should ALWAYS be included
			if (GetPlayer()->GetCulture()->GetCivLowestInfluence(false /*bCheckOpenBorders*/) == eOtherPlayer)
			{
				iItemValue *= 1000;
				iItemValue /= 100;
			}

			// If have influence over half the civs, want OB with the other half
			else if (GetPlayer()->GetCulture()->GetNumCivsToBeInfluentialOn() <= GetPlayer()->GetCulture()->GetNumCivsInfluentialOn())
			{
				if (GetPlayer()->GetCulture()->GetInfluenceLevel(eOtherPlayer) < INFLUENCE_LEVEL_INFLUENTIAL)
				{
					iItemValue *= 500;
					iItemValue /= 100;
				}
			}

			else if (GetPlayer()->GetProximityToPlayer(eOtherPlayer) == PLAYER_PROXIMITY_NEIGHBORS)
			{
				// If we're cramped then we want OB more with our neighbors
				if(GetPlayer()->IsCramped())
				{
					iItemValue *= 300;
					iItemValue /= 100;
				}
			}
		}
	}
 
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