[Idea] Diffrent techtree-links by nation

[BSPollux]

Just saw that 'missing techtree links' thread and came up with an idea:

Would it be possible to use the same set of techs (names, costs etc) but link them diffrently?

This could refelct the diffrent historical approaches that people have taken to reach the same goal. For instance the could be some civs that have mathematics linked closer to construction techs and some that link it closer to astronomy and calender. Then there could be some that have laws and government linked closer to military and some that have set it closer to religion or economy.

Even some realy small diffrences could change the possible strategys quite a lot and allow those that feel natural for a civ and block or delay those that seem alien to theire historical background.

 

[xxhe]

Really like your idea. Personally I don't know how to make it - at least through XML it is impossible.

I think this idea is similar to that of making different tech trees for different civs. But it's easier to achieve because we don't need to move the position of any building/units in the tech tree.

 

[Spatzimaus]

Would it be possible to use the same set of techs (names, costs etc) but link them diffrently?

Short answer: No.

Long answer: Nooooooooooooooooooooooooooo.

Really long answer:
It would be possible to create duplicate tech trees, where the dependencies are totally different, but these would have to be treated as distinct techs. That is, the Mathematics tech that the Chinese would get would be distinct from the Mathematics tech that the Russians would get. Different prerequisites, lead to different techs, whatever. You'd create a "Russian starting tech" and "Chinese starting tech", Disable each, hide them, artificially give each to the appropriate players, and then go up the line, where Mathematics-Chinese requires the usual prereq techs as well as the Chinese tech. Only the Chinese player could take it, because only the Chinese player would have that prerequisite. For simplicity's sake, you might just want to limit these to the four main Civ groups, i.e. European, Asian, African, American.

The first major problem would be that any benefits of that tech would have to be similarly duplicated. You'd have a Chinese Catapult being a distinct unit from a Russian Catapult, and the same goes for any buildings/improvement changes. Wonders wouldn't work at all, because since it'd have to be a distinct building, the whole "1 per world" limit wouldn't trigger correctly. (You COULD build this into the mod itself, so that only Asian civs can build the Great Wall, only European civs can build the Sistine Chapel, etc., but obviously this penalizes certain civs more than others, especially the African ones.)

Now, if you were also willing to rewrite the tech tree's Lua code, you could do this in a way that appeared transparent to the user. But it'd take a lot of work to make it look right, and there'd be some other compatibility issues involving the combination of AND with OR prerequisites.

The second problem would involve the trading or stealing of techs. You'd have to make sure they also checked to see if the tech in question is race-specific, and if so, find the alternate version appropriate to their civ. So you'd have a lot of compatibility issues.
This isn't just a problem with certain mods, it's part of the core game for barbarians and city-states. In addition to the traditional research method for city-states, both of these have a "stealing" mechanism where they'll gain techs as more and more major civs have it. I've confirmed that this can even trigger for Disabled techs, so you'd have a real problem where the Barbarian faction had unlocked all four (or more) research trees and gained units from all of them.

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Once we get DLL access this sort of thing should be relatively simple; we just need the ability to add a TechClass table for Technologies analogous to the UnitClass and BuildingClass tables. This'd allow for Buildings/Wonders/Units/Improvements/etc. to be set to require a TechClass entry instead of a Technology, which'd allow us to remove all of that duplication I mentioned above and avoid the stealing issues nicely. However, it'd require rewriting nearly every XML table in the database, so it's not exactly a small amount of work.

 

[BSPollux]

Thanks Spatzi for that very detailed answer.

 

[Spatzimaus]

Thanks Spatzi for that very detailed answer.

Race-specific tech trees for fantasy mods is a topic that pops up on a regular basis. It's unfortunate, but the game just isn't really structured to support that as a retrofit to the existing tree. Too much of the existing game is mixed together in a way that really isn't supportive of that sort of thing.

But all hope is not lost. While a TechClass setup would make this sort of thing trivial, the way it's structured is actually not bad for this if you specifically design a tree around that mechanism. The key is to not have multiple distinct trees, but to instead have a single tree with designed variation points that converge back into the main tree after only a brief deviation. As a practical example, think of Age of Empires; each race had very similar "tech trees", just with holes in different places.

So you could easily replace a single tech with race-specific alternatives, which had slightly differing prerequisites. The only headache is merging back together; this only works for techs whose following techs ONLY require them, because you're going to abuse the OR mechanism to do this.

For instance, consider a tree with techs A, B, and C, all at the same tier, right next to each other. You want these to be somewhat exclusive, where each civ has access to two of them but not the third, which means you need to work around the hole this creates. So, you create two more techs, D, and E, where D follows from A/B/C, and E follows from D. Like so:

A \
B - D - E
C /

You can make the stretch after D as big as you want, where it might go for an entire era before rejoining the "main" tree. The only limitation is that E must depend ONLY on D. If you want to create a whole block of techs that are race-specific then you can do that, but the tech that rejoins the main tree (E) MUST only depend on a single tech.

The catch is that you're not making a single tech D, what you do is create D1, D2, and D3 to replace D. D1 requires A and B but not C, D2 requires A and C but not B, D3 requires B and C but not A.
E then requires (D1, D2, OR D3), meaning every races' techs connect back together at that point. Since techs like E use an OR, they can't require any other technologies, which is what makes this incompatible with the existing tree. But again, designed tree, less problems.

So far so good. Now, we're still left with the problem of having the player have access to all three D techs. So we create race-specific techs 1, 2, and 3, where each race begins the game with one of those three but can never gain the other two.
To make things go even smoother, we should also create techs X, Y, and Z, where X is given to the 1 group and the 2 group, Y is given to the 1s and 3s, and Z to 2 and 3. (We need these for the "not 1" setup, so that we can use an effective OR merged with other ANDs.) So the "Human" civ has 1, X, and Y, while the "Zerg" has 2, X, and Z, etc. These techs don't even need to be given effects if you don't want any core differences between the races, but maybe you want the worker units for each race to have different stats or something.

With those, we can now change things a bit: D1 requires A, B, and 1, D2 requires A, C, and 2, D3 requires B, C, and 3. Since D1 doesn't require C, we can either make C require Z (which means anyone with 1 won't get it at all), or have it act as a dead-end tech for that civ.

All of this works in XML, with no need for any Lua hacks. The only question is the UI, which'd require a small amount of modification to only show the techs your civ has access to.

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The fact is though, it's mostly unnecessary to split techs like this. There's no rule that states that a Unique Unit/Building has to be at the same tech as the unit it replaces. So you could easily put the European Swordsman at one tech, the Asian Swordsman at another, and the American Swordsman at a third one. It's more suited towards the total-conversion concept, where entire eras will be distinct.

But again, there'd be problems with the barbarian faction, and city-states, unless you made sure they had limited access to the rewards for these techs. The existing UnitOverrides and BuildingOverrides tables actually work well for this.