Discussion: Where do we want to go with canals?

axatin

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I would like to open a discussion about canals, the advantages and disadvantages of their current implementation and where we would like to go with them (see also the discussion in Proposal (2-91), from which I've taken some arguments and ideas). Let me start with a recap of the current implementation:

- Owned Forts, Citadels and Cities count as canals (i.e. are accessible for owned naval units) if they are next to a water tile
- this implies in particular that the maximum length of a (useful) canal is 2
- Canals are accessible for owned and foreign cargo ships
- Cities that are next to a lake can build naval ships if (and only if) the lake is connected to the ocean with a canal
- Cities that are next to a lake cannot build coastal buildings (lighthouses etc.) under any circumstances

Problems / edge cases with this implementation:
- Cities that can't be attacked from the ocean can produce naval ships, which can be seen as unfair
- lake cities connected by a canal are a hybrid: they can build ships, but no coastal buildings. why?
- the current system can be abused to cancel sea trade routes before they are finished (by replacing a fort with another improvement)

The problem with cargo ships (if it is seen as a major abuse) could be solved by making canals inaccessible to cargo ships. On the other hand, canals could be made indestructible, or at least require more time to destroy (this would require a new game mechanic. would it be worth it?). The hybrid status of lake cities with canals can be changed in both directions: by allowing coastal buildings in those cities, or by prohibiting the construction of ships in lake cities altogether.

The fact that canals are accessible for owned ships and not for foreign ones makes then situationally a strong advantage in defensive wars. If desired, we could discuss opening canals also to foreign ships (afaik there's even an SQL option for this currently, but I don't know if it works).

The issues with the current implementation of canals would gain more significance if we wanted to buff canals by making them connect also non-lake cities to the ocean.

Lastly, canals could also be completely reworked, separated from the current fort/citadel system and offered as a separate improvement like in this mod.

What are your thoughts about the topic and the issues mentioned here? And what is your opinion on which direction we should go with canals? Do you want them to be buildable in more situations or give more benefits to them, or do you feel that they are currently already too strong and that the current system is already too exploitable?
 
All things considered, less-is-more here when it comes to canals -- while the game itself can handle them just fine, the AI can't optimize the decision of where to build a really long canal, it took years to get them to build the 1-2 tile versions. I am doubtful longer canals will ever be feasible for AI.

I'd love to see those art assets implemented though, and for the canals to be distinct from forts, as well as some of the minor quirks fixed in OP. Probably fits best as mod-mod though. There's another mod that makes use of these, haven't tried any of em but iirc the implementation requires forts built first and then the canal to replace it. Something like this might work for VP as well.

In addition to OP, I'd like to see embarked units stay embarked when they enter a canal, maybe unless they idle with full movement unused in the canal tile. This would require dev attention though, can't be accomplished in modmod afaik
 
We can have the canal improvement and restrict it to be only buildable near water. Then they can be made indestructible (but pillageable, to remove the yields), which solves the cargo ship problem. Not sure if we can also make foreign ships use canals.
 
I'm fine with extended canal being a DIY wonder only available to human players, as everyone would be able to go through it if they can pass through your border (if you build a city at a strategic location/choke point it would be the same).
 
Just because we can doesn’t mean we should. The current canal/fort ability makes both functions of that 1 improvement more valuable together, and splitting them makes 2 very circumstantial improvements. It’s more elegant and useful as it is now, and the upside of splitting them is purely graphical.
 
Using forts and citadels as canals feels weird to me. I would rather simply choose to play on a more watery map.

On standard maps with a pair of continents, there is no sea passage for ships at one of the poles due to ice. The founding of a city with a couple of forts often makes it possible to create a sea route so as not to go around the mainland along the equator.
 
There's another mod that makes use of these
in reference to above: steam workshop link.

description copied from that implementation (bolded the ones I like)
- Allows Water Passage for Naval Units and Cargo Ships. Yields: +1 Culture and +2 Gold.
- Adjacent Tile Yields: +1/2/3 Gold to Trading Posts, Villages, and Towns.
- PrereqTech: Gunpowder. Can only be built on completed Fort Improvements.
- Balance: -20% Combat Strength for Land Units; Naval Units cannot attack.
- Panama Canal World Wonder grants +1 Food to all Canal tiles.

The current canal/fort ability makes both functions of that 1 improvement more valuable together
I think there are cases where you just want one or the other -- perhaps not the common case, but it happens. Also, having a fort available separately from a canal might allow for adjustments to address the following OP concern, which seems valid:
The fact that canals are accessible for owned ships and not for foreign ones makes then situationally a strong advantage in defensive wars. If desired, we could discuss opening canals also to foreign ships
 
Preventing lake cities from building naval units feels like the simplest way to improve consistency. I'm biased though, you don't get big lakes on small-ish maps so they're easily to sacrifice. I'm with pdan on not adding a new improvement, but I'd be more welcoming to the idea if it was somehow unique (ex: a one-time canal project available to water/lake adjacent cities that spawns an expendable "canal builder", too much work tho)
 
I think grand canals have too many issues to make easily available. I think the rules I'd be happy with for building would be: 1. must be adjacent to coast/lake; 2. cannot be adjacent to more than one canal. This way you can bridge 2-tile gaps without a city or citadel, and if you do commit a city you can possibly have a 5-length canal. Of course forts would need to no longer work as canals (or maybe they're included in the exclusion list, with other canals?).

Probably too much effort for the meager pay-off, but the assets are pretty good, wouldn't mind seeing them in the game. The yields on them are a little weird though, probably needs some tuning.
 
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I think grand canals have too many issues to make easily available. I think the rules I'd be happy with would be: 1. must be adjacent to coast/lake; 2. cannot be adjacent to more than one canal. This way you can bridge 2-tile gaps without a city or citadel, and if you do commit a city you can possibly have a 5-length canal. Of course forts would need to no longer work as canals (or maybe they're included in the exclusion list, with other canals?).

Probably too much effort for the meager pay-off, but the assets are pretty good, wouldn't mind seeing them in the game. The yields on them are a little weird though, probably needs some tuning.
Just adjacent to water is enough. Cities also need to be adjacent to water to be enterable by ships.

It should have no base yields, but +gold (and maybe culture?) when a trade route passes through it.

Note that there's no way to allow foreign military units to enter a city functioning as canal peacefully, even if the canal improvement is made enterable.
 
I think grand canals have too many issues to make easily available. I think the rules I'd be happy with for building would be: 1. must be adjacent to coast/lake; 2. cannot be adjacent to more than one canal. This way you can bridge 2-tile gaps without a city or citadel, and if you do commit a city you can possibly have a 5-length canal. Of course forts would need to no longer work as canals (or maybe they're included in the exclusion list, with other canals?).

Probably too much effort for the meager pay-off, but the assets are pretty good, wouldn't mind seeing them in the game. The yields on them are a little weird though, probably needs some tuning.
I like this in general to allow an increased length for canals. right now max is 2 and one has to be a city. I'm also ok with building ships in lake connected cities. Just think about the Bosporus and black sea.

being able to go through a canal at a narrow point of a content with ships is rather "cool". just like the panama canal. Maybe a tile limit, max 5 canal tiles or something like that could be done if some think this is too gamey. Or like with many things, if you think it's gamey are cheese, don't use it. The AI has advanatges as well so not like it is fair to begin with on high level and not everyone needs it to be "fair" and play for fun even if the AI had can't deal with the feature as fully as a human player can.
 
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For one I think the changes should probably be put in a modmod, I think the more changes that are added to the base mod in general just serve to potentially break older mods.

That aside, I think the proper implementation is to allow only naval buildings to be constructed from canals but not ships. There should be a risk factor in being able to produce ships given how much stronger a powerful navy can be over a powerful army on some maps, and so by letting cities 1 tile away from the coast produce ships you guarantee a city unable to be sieged from sea but able to produce a potent naval army which is just busted. Same thing for lakes that are 2 tiles from the coast. Being able to give cities that aren't directly coastal access to the yields from the lighthouse/harbor/seaport I think is totally fair though, given how utterly crap those tiles are generally, and would make it more tolerable for Tradition gameplay which generally does not want to settle coastally because of the bad yields and defense requirements.

All this, and I think cross continental canals should be a thing again. It's a fun way to use your GG's and isn't really broken because it takes a lot of military success (or use of free GP's) to access it depending on continent size. It does not matter if the AI can use it properly because ultimately the game ought to be designed to be enjoyable by the player, even if that's at the expense of the AI being fairly treated.
 
I think canals have developed to be in a good spot over time. They open interesting options and the AI has become quite good at building them and also sending ships to attack in inland seas.

There are some minor inconsistencies, but overall I like the current setup. If I would change anything, it would be allowing lake cities to build coastal buildings AND ships.

As for complaints about very defensive cities: it not only helps the player defend, but also the AI. Some cities become very hard to take in a domination game. Since I consider domination as the easiest victory type, I am perfectly fine with this situation.
 
If it isn't too hard to code...

Canal should be a separate improvement that's indestructible
Fort and Citadel can no longer be entered by ships
Canal should be enterable by rival ships
A city should be allowed to build ships and coastal buildings if and only if the city can be reached by rival ships from the ocean (i.e. not blocked by other cities in the path)
 
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