Hi, Birken!
Hats off to you, I really like your train of thought here.
My main observation here is going to be that the game already rewards you for a lot of things like you mention, along with a system of soft limits and rewards for keeping them. These are: opinion (more importantly) and income (less importantly). Both of them, but especially opinion, react to what you do now or did in the past and also determine what you can do in the future (or more of it vs less, earlier vs later etc.).
I'll elaborate, if you have the time and care to read more about this idea:
For example imagine your character is a good ruler, who tries to govern well and bring prosperity to his (or her) realm, takes the Rulership focus because that's what he or she cares the most about, which is WoL's figurative embodiment of aspirations toward good rule. You get traits, modifiers etc., your stewardship stat improves (as well as other stats for up to +3 total) and so on. So what's the overall effect of this?
For starters:
'Liege is Just' = +10 vassal opinion
'Liege is Diligent' = +10 vassal opinion
stackable with 'Both are Just/Diligent' for another +10 per trait
'Respected ruler' = +10 opinion from all vassals
The total is:
+30 opinion with all vassals, no matter what
+40 to +50 if they share the same values and priorities ('Both Just/Diligent' alone)
and +10 to +20 with external rulers
This also stacks with bonuses from being Kind and Charitable (good person) and/or Strong and Brave (strong ruler, 'battle king').
Your reward here consists in all of the things that the opinion boost allows you to do, notably by offsetting opinion penalties for your other actions. These can be various things across all aspects of the game, for example:
– peace and calm in your realm, as people are far less likely to join factions against you (sometimes at some point this gets to the point of there being no factions, there is not even any single rotten apple who would spymaster other vassals into joining the faction)
– external peace, as there are fewer people who dislike you, even stronger neighbours with claims on your territory cut you a lot of slack
– less personal danger from plots, assassination attempts etc.
– much more leeway (notably offsetting the 'Raised Levies' penalty) for your wars and especially their duration
— more levies as well, at +30 or especially +50 opinion it's the same effect as if you had Sent Gifts to your vassals before calling the banners
– more tax money, depending on what kind of vassal types and tax settings you have
– you can change crown and demesne laws without destabilizing the realm
– you can even do things like taxing your feudal vassals, which are normally a no-go zone
– you get away with Short Reign (or being an Ugly female, or educating your heir with a foreign culture etc.)
– the Pope's opinion of you is likely high enough to prevent excommunication
– more of your vassals will vote for your chosen heir in Elective (and you can get away with changing succession laws if you want/need to, which is sometimes difficult if your vassals are of the same dynasty as you)
– greater economic prosperity and development, especially considering that:
Your Stewardship stat increases (+2 from Just, +2 from Ambitious, +1 from Diligent, +3 from Administrator, +3 from the focus itself) translate into higher demesne limit (which means more income and levies, as well as investment opportunities, titles for your sons etc.) and directly into higher income (even higher if you always diligently take care to invite stewards with high stats to serve on your council).
More income simply means you can do more stuff… or you can do the same stuff but earlier. This includes especially construction of tax-generating buildings and new holdings for further improvement of your income (sometimes with your Steward hastening the construction).
And, like I mentioned before, this stacks with the perks of being a nice person, good diplomat or battle king, further increasing your opinion and the bonuses and — ultimately — opportunities it gives you.
So you get amply rewarded in the game for being a good ruler, a good person, and for diligence and effort (both the character's and the player's, e.g. the benefit of always taking care to have good councillors is obvious, and then you can be even more diligent and breed and educate future councillors to advice your heirs).
See? The meat is already there. It's just that the boons are not always seen by players, because the 'carrot and stick' chain — the causation chain, if you prefer — is a bit longer and more complicated, it's not always easy to notice for some people, it may be easy to confuse the rewards of being a good ruler with a mistaken impression that the game is easy in general.
Penalties are also there in the game, for crossing the soft limits of opinion: For example: neglect stewardship, neglect being Just or Diligent, allow yourself to be Arbitrary... and you're going to lose these powerful boons and even get some penalties delivered simply by the opinion system and income (as the medium). Be a bad person and/or a bad ruler, and vassals and neighbours will hate you, attack you, plot against you etc. But many players will confuse this with a mistaken impression that the game is hard in general (which it is not, it's more in the medium range).
My conclusion is that there is already a great system of both soft limits and rewards in-game (which may sometimes be hard to tell apart, as it's quite fluid, as it should be). The 'difficult' part here is that those rewards simply are not explicit perks.
Hence, if you want to bring out trade-offs, soft limits, rewards and soft penalties, perhaps what you need to do is be more explicit about the stuff that you have already included in the game. This could be done with events, dialogues, Chronicle entries, some visual rewards (badges of honour akin to Steam achievements but inside your game and not on your Steam profile), but it strikes me as a task for the marketing department and community managers — to call more attention to player tutorials, guides, CK2 Wiki, gameplay vids, AARs, educational screenshots and everything else like that.
Or get a writer to do a write-up (with pictures, tables and diagrams) of what already is in the game but emphasizing the links and synergies.
Additionally, on the design/scripting front, you may want to:
1. Long-term: Bring diplomacy (education trait, actions etc. as opposed to passive modifiers) to the same level of development that stewardship and governance already has in this game.
Perhaps warfare could use it also, but first of all you want to think about replacing the 3-year 99% war score limit with something less artificial and making AI consider the pros and cons of capitulating before 100%, especially as attacker. This is because allowing your entire army to be butchered to 0 and then again a couple of times after reraising is very dangerous to realm stability — it makes faction power rise and can cost you your throne; AI should be conscious of this and not suicidally stubborn 90% of the time like it is now.
Religion has a good complex set of passive modifiers — Church View on X — but in the longer term you you could make the Pope more active, along with cardinals and local churchmen. I would like to see excommunication used a bit more often than now. It shouldn't be an everyday occurrence but perhaps more frequent than it is now anyway. Other bonuses and maluses could be awarded through dialogue windows with the Pope.
2. In a shorter term perhaps do something with the 100/100 hard tie-breaker between pope and liege. The Pope could also give it over to you if he likes you or especially if you are crusading (Louis IX had that kind of agreement with the then-Pope). Or you could just remove the 100 cap for the purposes of comparison alone and compare the +120 vs +240 sum total of modifiers in the background while displaying +100 for both.
3. Tell Groogy to give up on automatically making you join your allies' wars. That idea goes completely against the idea of soft limits and trade-offs. It's almost like AI playing the game for you.
4. Remove hard blocks from diplovassalization while still keeping the requirements difficult to meet, and make opinion count for more, not less (i.e. the opposite direction from the recent patches). This is because opinion is largely a product of your actions and your personality, hence choices and tradeoffs you make. If you reduce the impact of opinion, relying instead on de iure, religion, culture as hard blocks, then you make the game more deterministic and hardcoded.
There is no justification for the hard blocks existing right now, other than anti-blobbing/balance. But you can achieve that goal by making those conditions hard but not impossible to meet.
If you are worried about gifts, perhaps include a check against them while checking opinion.
Most importantly, small AI rulers facing the threat of being wiped out in a single holy war from any 1 of 5 neighbouring enemies should look for protection and should not turn it down easily when offered. Losing your independence is better than losing your land and possibly life.
5. Introduce a form of badboy by making AI rulers attempt to replace you with a claimant when their patience runs out. This would be a bit similar to excom for notorious misdeeds.
6. Increase the risks for Seducers, in particular, as their life is unrealistically low on risk right now. Often you have no CB even if they are exposed trying to seduce your own wife. They should be facing the threat of capture, imprisonment, castration (even outside of Byzantine culture), execution, excommunication, war.
7. The same goes for other forms of infidelity and sexual scandals.
8. Marrying within your rank doesn't really need a reward, because it's the typical thing to do anyway, but marrying up doesn't seem to raise your status other than increasing your children's rank for marriage and giving you some prestige. This can already be felt as a benefit, but perhaps some more recognition could be advisable.
Marrying below your rank does harm your prestige, but it still isn't penalized enough, there is no opinion malus among your aristocratic vassals etc. Consider the outrage over Edward IV and Elizabeth Woodville, for example. There should be serious downsides to marrying 3–4 tiers below but especially marrying a lowborn as a king or emperor.
On the other hand, all the foreign blood in your dynasty's veins from consistently marrying foreign royals could perhaps lead to some resentment among more nationalist-minded vassals.
9. 'Conveniently' dynasty prestige is a bit underutilized, so perhaps a first step could be to make it reflect the rank of people married, not only titles held.
10. I would perhaps also add war prestige (but not the kind of prestige you get every month for holding your titles, that's already covered), crusades won, empires and kingdoms founded etc. to dynasty prestige to make it more varied/deeper than just titles held. This would more fully reflect the real standing and fame of your dynasty for marriage purposes.
11. Huge character prestige should matter more than it already does, rather than its perks being hard-capped at a low number. Being able to create a custom empire at 8K is a nice exception, but I'd like to see more. When rulers have like 5K prestige, their word should hold sway outside their borders. They should have a larger role in international politics, diplomacy etc., not only wars.
12. Treason could use more serious consequences. Larger revocation allowance (1 title often means nothing). More use of execution and banishment by the AI.
13. If you play it too feudal as a Patrician, you should probably face some resentment from republican hardliners. I love the way it's possible to own large feudal fiefs, fight normal wars, make the dogeship practically hereditary in your family, even neglecting trade all the while. But I'm pretty sure in real life it would ruffle some feathers.
14. This might not be worth the bother (especially since you can modify your CoA on your own any way you want), but nobles would often 'impale' or 'quarter' their arms with those of their important wives, especially heiresses, last of the line etc. Also sometimes lieges rewarded them by adding something prestigious to their CoAs, sometimes even elements of the liege's own CoA.
15. Another minor thing, but, historically, not all people titled as princes or princesses were historically children of kings and emperors, so perhaps you might want to make it possible to somehow acquire princely status for your family despite the lack of a full kingdom. Historically this was the case with ethnic leaders, think tribal chiefs converting into feudal dukes, which is a bit similar to petty kings. Children of petty kings should be titular princes, if not necessarily ranking above the children of normal dukes.
16. It would be great to be able to earn your way toward being elected the king or emperor of an uncreated title, especially one that existed before but was destroyed, especially if you have a claim on it but not enough land, by your fellow vassals of the same title. Basically independents getting together and electing a king to rule the recreated/unified kingdom. Especially for Ireland, Wales, Saxon England, Russia.
17. Giving your liege more levies than required and/or more than your opinion would normally suggest is currently not possible. Well, it should be possible because what's there in feudal law that says you are allowed to provide no more than such and such number of troops? The game seems to be based on the presumption that characters want to do as little as possible under the feudal contract, which certainly need not be the case, given the various personalities and opinions etc.
Enabling this could also eliminate the need to attack the armies of your liege's enemies with your own troops without the ability to affect the war score, which players end up doing anyway (I've done it a lot myself).
18. The game kinda presumes that you want to do the minimum you can get away with for your liege, in general. I think it would be interesting to open up a way to actually serve your liege
19. I would make AI lieges construct buildings in their vassals' holdings (including the human player) if there is a benefit to the liege — starting from shipyards and fortifications. Shipyards because they tend to serve the entire realm rather than just the count or duke, and forts because your ability to resist sieges is also important to your liege's war scores in his own wars.
20. I would take away characters' traits for actions inconsistent with those traits. That would be a soft limit in itself: yes, you can break your word, but don't expect to keep your Honest trait (and +2 diplo). Yes, you can incur Tyranny, but don't expect to keep your Just trait (and +2 stewardship).
21, Last but not least, concerning blobbing, overextension etc., it would be a good thing to make laws not automatically obeyed. To what extent your laws and your commands are obeyed should depend on a number of things, including prestige, respect, sympathy, distance from capital, personal loyalties and moral codes.
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Since you mentioned 'having all your titles and vassals as within the dejure of your primary title':
1. Secondary titles also matter, they can be perfectly reasonable legit holdings inherited e.g. from one's mother, who was the heiress of an old dynasty ruling there for many centuries (think James I/VI inheriting England). So I think primary title alone would be too restrictive.
2. Still, I can think of some bonuses for owning your full de iure and/or owning nothing outside it:
– completing your full de iure puts you somewhere close to modern nation states or makes you a restorer/liberator/whatever kind of personage; there is also no stain on your honour from foreigners controlling parts of your kingdom; regarding bonuses I would think about prestige or a free law change, or increasing your Crown Authority without the usual opinion penalties
– on the other hand, not owning anything outside your de iure puts you somewhere in the Content & Temperate range; it could also mean you focus more on internal than external affairs; you could perhaps get away with higher crown authority, get more demesne limit/centralization, get some piety, be seen as less of a threat by the AI (as you are clearly not an expansionist.
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Next, I agree with the idea of rewarding fidelity/chastity. Perhaps also some kind of 'fair play' rewards for characters that don't fabricate claims, sow dissent, assassinate people, make chancellors disappear, torture prisoners, give or take bribes etc.
This may be a bit off-topic, but I certainly agree with keynes2.0 that fighting large opponents for small pieces of land is very tedious right now. However, I don't agree that war score should be completely scaled down to the size of the war goal. That would unnecessarily restrain large defenders who wanted to keep on defending their stuff, or large attackers who wanted to keep advancing, despite initial setbacks. Just perhaps make the clock tick faster or enable more ways of combining claims. I don't really know.
What I would personally like to see is some kind of a bonus for not being cruel or harsh with your enemies and errant subjects. Similar to Merciful +10 opinion for releasing imprisoned vassals, but with more triggers and more consequences.
It just isn't explicitly packaged as an overextension penalty of the kind you have in EU3.
