taw's blog: What if all EU4 idea groups were good

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Many EU4 idea groups are bad. There are two sides of this badness - power level and identity.

Power level is relatively easy to analyze objectively. I once created an algorithm to rank all EU4 idea groups. This was 5 years ago, patches completely changing game balance happened, so those specific values are outdated. Not to mention original algorithm had some minor issues.

I try to keep the scoring algorithm more or less up to date, so assuming I didn't miss any important changes, here's the 1.30 latest ranking.

Everything in this post is about single player only, multiplayer meta is drastically different.

Basic Ideas Ranking

9.09 Expansion Ideas
7.65 Diplomatic Ideas
6.00 Exploration Ideas
5.66 Religious Ideas
5.58 Administrative Ideas
5.35 Influence Ideas
4.67 Humanist Ideas
4.33 Plutocratic Ideas
3.89 Trade Ideas
3.89 Aristocratic Ideas
3.80 Quantity Ideas
3.33 Offensive Ideas
3.13 Innovative Ideas
2.92 Quality Ideas
2.75 Espionage Ideas
2.26 Defensive Ideas
1.58 Economic Ideas
1.12 Maritime Ideas
0.75 Naval Ideas

National Ideas Ranking

10.75 Holy Roman Ideas
10.27 Asturian Ideas
10.17 Great Yuan Ideas
9.60 Imperial German Ideas
9.50 Great Qing Ideas
9.17 Roman Ideas
9.12 Kiwi Ideas
8.93 Andalusian Ideas
8.83 Russian Ideas
8.25 Synthetic Ideas
8.04 Icelandic Ideas
7.98 Castilian Ideas
7.92 American Ideas
7.85 Oirat Ideas
7.67 West Indies Ideas
7.54 Jerusalem Ideas
7.24 Oda Ideas
7.19 French Ideas
7.18 Herzegovinian Ideas
7.09 Rûmi Ideas
6.96 Yamana Ideas
6.85 Lotharingian Ideas
6.85 Italian Ideas
6.79 Carib Ideas
6.74 Spanish Ideas
6.69 Norwegian Ideas
6.66 Mongolian Ideas
6.65 Mughal Ideas
6.56 Austrian Ideas
6.55 Leonese Ideas
6.54 Mysorean Ideas
6.37 Hindustani Ideas
6.37 Kazani Ideas
6.36 Hadramhi Ideas
6.34 Golden Horde Ideas
6.34 Ottoman Ideas
6.24 Iroquois Ideas
6.19 Japanese Ideas
6.18 Sardinian Ideas
6.10 Australian Ideas
6.10 Crimean Ideas
6.07 Rajputana ideas
6.03 Aq Qoyunlu Ideas
5.97 Canadian Ideas
5.93 Irish Ideas
5.92 Bharathi Ideas
5.86 Deccani Ideas
5.86 Prussian Ideas
5.84 Saluzzo Ideas
5.83 Anatolian Ideas
5.81 Najdi Ideas
5.77 Candarid Ideas
5.74 Chernihiv Ideas
5.72 Karamanid Ideas
5.70 Nagpuri Ideas
5.67 Burmese Ideas
5.65 Imagawa Ideas
5.63 Nepali Ideas
5.58 Sardinian-Piedmontese Ideas
5.56 Ayyubid Ideas
5.54 Delhian Ideas
5.54 Qara Qoyunlu Ideas
5.54 Desmondian Ideas
5.51 Bosnian Ideas
5.46 Chagatai Ideas
5.44 Trent Ideas
5.42 Divine Ideas
5.41 Manipur Ideas
5.40 Knights Hospitaller Ideas
5.39 Khorasani Ideas
5.39 Greek Ideas
5.36 Native Ideas
5.36 Manchu Ideas
5.33 Antemoro Ideas
5.30 Colognian Ideas
5.29 Three Leagues Ideas
5.25 Tarascan Ideas
5.25 Wallachian Ideas
5.22 Tibetan Ideas
5.22 Polish Ideas
5.21 Date Ideas
5.19 Mantuan Ideas
5.19 Mushasha Ideas
5.17 Dalmatian Ideas
5.15 Muscovite Ideas
5.13 Swedish Ideas
5.13 Moluccan Ideas
5.11 Ryazan Ideas
5.08 Byzantine Ideas
5.08 Pegu Ideas
5.05 Bremen Ideas
4.95 Bulgarian Ideas
4.94 Saxon Ideas
4.92 Asakura Ideas
4.92 Shoni Ideas
4.91 Münster Ideas
4.90 Teutonic Ideas
4.89 Kievan Ideas
4.88 Epirote Ideas
4.83 Timurid Ideas
4.80 British ideas
4.77 Provençal Ideas
4.76 Sukhothai Ideas
4.75 Otomo Ideas
4.75 Hungarian Ideas
4.74 Kaffan Ideas
4.73 Westphalian Ideas
4.72 Rigan Ideas
4.71 Perugian Ideas
4.71 Tokugawa Ideas
4.70 Gond Ideas
4.69 Romanian Ideas
4.67 Jan Mayen Ideas
4.66 Utrecht Ideas
4.66 Great Shun Ideas
4.65 Kitabatake Ideas
4.63 Assamese Ideas
4.63 Ajami Ideas
4.62 Rassid Ideas
4.62 Manx Ideas
4.62 Ethiopian Ideas
4.61 Württemberger Ideas
4.60 Ryukyuan Ideas
4.59 Bohemian Ideas
4.56 Cilli Ideas
4.56 Sicilian Ideas
4.55 Papal Ideas
4.55 Holstein Ideas
4.55 Palatinate Ideas
4.54 Hojo Ideas
4.53 Nanbu Ideas
4.53 Trierian Ideas
4.53 Dai Viet Ideas
4.52 Dithmarscher Ideas
4.52 Liège Ideas
4.51 Aachen Ideas
4.51 Kanem Bornuan Ideas
4.51 Mapuche Ideas
4.50 Brandenburg Ideas
4.50 Georgian Ideas
4.49 Cossack Ideas
4.48 Bengal Sultanate Ideas
4.48 Rostov Ideas
4.47 Burgundian Ideas
4.46 German Ideas
4.43 Alaskan Ideas
4.43 Nizhny Novgorod Ideas
4.43 Daimyo Ideas
4.42 Bamberger Ideas
4.42 Lithuanian Ideas
4.41 Shimazu Ideas
4.40 Maravi Ideas
4.38 Satake Ideas
4.37 Kongo Ideas
4.37 Athenian Ideas
4.37 Tumbuka Ideas
4.36 Medri Bahri Ideas
4.35 Butua Ideas
4.34 Uesugi Ideas
4.33 Rajput Ideas
4.32 Moravian Ideas
4.31 Kildarean Ideas
4.31 Granada Ideas
4.30 Khmer Ideas
4.30 Thüringian Ideas
4.29 Malian Ideas
4.29 Swabian City-State Ideas
4.28 Ansbach Ideas
4.25 Swabian Ideas
4.25 Yarkandi Ideas
4.23 Franconian Ideas
4.20 Novgorod Ideas
4.19 Butuan Ideas
4.19 Colonial Ideas
4.18 Ogasawara Ideas
4.16 Sindhi Ideas
4.15 Montferrat Ideas
4.14 Mossi Ideas
4.13 Ito Ideas
4.13 Client State Ideas
4.12 Kikuchi Ideas
4.11 Brunswicker Ideas
4.10 Lan Na Ideas
4.09 Scottish Ideas
4.09 Hanoverian Ideas
4.08 Jurchen Ideas
4.08 Lur Ideas
4.06 Trebizond Ideas
4.06 Bregenzer Ideas
4.06 Arakanese Ideas
4.06 Dortmund Ideas
4.04 Ilkhanid Ideas
4.04 Naxian Ideas
4.04 Ouchi Ideas
4.03 Chosokabe Ideas
4.03 Québécois Ideas
4.02 Tsutsui Ideas
4.02 Luxembourg Ideas
4.01 Isshiki Ideas
4.01 English Ideas
4.00 Farsi Ideas
3.98 Aztec Ideas
3.96 Ormond Ideas
3.93 Ajuuraan Ideas
3.93 Shan Ideas
3.92 Luban Ideas
3.91 Semien Ideas
3.91 Tuscan Ideas
3.91 Afghan Ideas
3.90 Chinese Ideas
3.90 Texan Ideas
3.88 Finnish Ideas
3.88 Savoyard Ideas
3.86 Armenian Ideas
3.86 Bahmani Ideas
3.86 Rothenburg Ideas
3.85 Great Ming Ideas
3.85 Hormuz Ideas
3.84 Beninese Ideas
3.82 Offaly Ideas
3.81 Huron Ideas
3.81 Berg Ideas
3.80 Cornish Ideas
3.79 Songhai Ideas
3.79 Pskovian Ideas
3.78 Hatakeyama Ideas
3.78 Maratha Ideas
3.77 Breton Ideas
3.76 Punjabi Ideas
3.76 Brazilian Ideas
3.76 Amago Ideas
3.75 Sonoran Ideas
3.75 Persian Ideas
3.74 Odoyev Ideas
3.74 Thomondian Ideas
3.74 Samtskhe Ideas
3.73 Mainzian Ideas
3.73 Tirhuti Ideas
3.72 Ando Ideas
3.72 Dhundhari Ideas
3.71 Ruthenian Ideas
3.70 Yemeni Ideas
3.70 Chiba Ideas
3.69 Mayan Ideas
3.68 Clevian Ideas
3.67 Gujarati Princedom Ideas
3.66 Shawnee Ideas
3.66 Estonian Ideas
3.65 Krakowian Ideas
3.64 Piratical Ideas
3.64 Javan Ideas
3.63 Garhwali Ideas
3.63 Moldavian Ideas
3.63 Catalan Ideas
3.62 Bayreuther Ideas
3.60 Mexican Ideas
3.59 K'iche Ideas
3.58 Vermont Ideas
3.58 Anhalt Ideas
3.58 Milanese Ideas
3.58 Air Ideas
3.58 Utsunomiya Ideas
3.55 Hessian Ideas
3.55 Mesoamerican Ideas
3.54 Ashanti Ideas
3.54 Shirvani Ideas
3.54 Tyrconnell Ideas
3.53 Malabari Ideas
3.53 Goslar Ideas
3.53 Lan Xang Ideas
3.51 Yi Ideas
3.50 Pagarruyung Ideas
3.50 Garjati Ideas
3.49 Leinster Ideas
3.49 Theodoro Ideas
3.48 Mori Ideas
3.48 Genevan Ideas
3.48 Circassian Ideas
3.48 Ladakh Ideas
3.48 Orleanaise Ideas
3.47 Nepalese Princedom Ideas
3.47 Gutnish Ideas
3.46 Miao Ideas
3.45 Muiscan Ideas
3.45 Nuremberger Ideas
3.44 Siddi Ideas
3.44 Laotian Ideas
3.44 Shiba Ideas
3.44 Ardabili Ideas
3.43 Neapolitan Ideas
3.42 Sinhalese Ideas
3.42 Bavarian Ideas
3.41 Portuguese Ideas
3.41 Yaroslavlyian Ideas
3.41 Sadiyan Ideas
3.41 Northumbrian Ideas
3.40 Transylvanian Ideas
3.39 Kutai Ideas
3.39 Takeda Ideas
3.39 Creek Ideas
3.39 Sami Ideas
3.37 Mewari Ideas
3.36 Bolognese Ideas
3.35 Fulani Jihad Ideas
3.34 Welsh Ideas
3.34 Munster Ideas
3.34 Imerina Ideas
3.34 Polotskian Ideas
3.34 Pacific Northwest Ideas
3.33 Kurdish Ideas
3.33 Ava Ideas
3.31 Tverian Ideas
3.31 Slovak Ideas
3.31 Kangra Ideas
3.31 Tyrone Ideas
3.30 Croatian Ideas
3.29 Deccani Sultanate Ideas
3.27 Interlacustrine Ideas
3.23 Cherokee Ideas
3.20 Wurzburgian Ideas
3.18 Vijayanagar Ideas
3.17 Mutapan Ideas
3.16 Frankfurter Ideas
3.16 Bengali Ideas
3.16 Meath Ideas
3.16 Barbary Corsair Ideas
3.15 Sumatran Ideas
3.14 Arabian Ideas
3.14 Dutch Ideas
3.12 Guarani Ideas
3.12 Lunda Ideas
3.12 Vindhyan Ideas
3.11 Beloozero Ideas
3.10 Swahili Ideas
3.10 Gelre Ideas
3.10 Nubian Ideas
3.09 Hosokawa Ideas
3.09 Highlander Ideas
3.08 Korean Ideas
3.08 Danish Ideas
3.08 Zambezi Ideas
3.08 Couronian Ideas
3.07 Mindanao Ideas
3.06 Evenk Ideas
3.03 Incan Ideas
3.03 Saxe-Lauenburg Ideas
3.02 Serbian Ideas
3.00 Arawak Ideas
3.00 Tripuran Ideas
3.00 Galician Ideas
2.99 French Ducal Ideas
2.98 Kuban Ideas
2.97 Veronese Ideas
2.97 Ulmer Ideas
2.91 Baluch Ideas
2.91 Ainu Ideas
2.88 Aragonese Ideas
2.88 Mamluk Ideas
2.87 Corsican Ideas
2.87 Toki Ideas
2.87 Swiss Ideas
2.85 Hejazi Ideas
2.84 Pisan Ideas
2.83 Orissan Ideas
2.83 Lusatian Ideas
2.80 South Indian Ideas
2.80 Caspian Ideas
2.79 Mazovian Ideas
2.79 Lüneburger Ideas
2.78 Cypriot Ideas
2.78 Urbinate Ideas
2.78 Montenegrin Ideas
2.78 Tapuian Ideas
2.76 Jaunpuri Ideas
2.75 Ulster Ideas
2.72 Silesian Ideas
2.72 Zaporozhian Ideas
2.70 Hausan Ideas
2.68 Norman Ideas
2.67 Tunisian Ideas
2.66 Hamburger Ideas
2.64 Sligonian Ideas
2.64 Malayan Sultanate Ideas
2.64 West African Ideas
2.63 Gujarat Sultanate Ideas
2.63 Ayutthayan Ideas
2.62 So Ideas
2.61 Caucasian Ideas
2.59 Siberian Ideas
2.58 Danziger Ideas
2.57 Lorraine Ideas
2.57 Ragusan Ideas
2.57 Sistani Ideas
2.56 Malagasy Ideas
2.56 Indian Sultanate Ideas
2.56 Malvi Ideas
2.54 Clanricarde Ideas
2.54 Ionian Ideas
2.52 Betsimisaraka Ideas
2.52 Mogadishan Ideas
2.51 Dahomey Ideas
2.49 Brabant Ideas
2.49 Pomeranian Ideas
2.47 Dali Ideas
2.47 Permian Ideas
2.46 Pueblo Ideas
2.44 Al-Haasa Ideas
2.44 Omani Ideas
2.43 Cham Ideas
2.43 Smolenskian Ideas
2.42 Ferraran Ideas
2.42 Hanseatic Ideas
2.40 Berber Ideas
2.40 Italian Ideas
2.39 Chimu Ideas
2.39 Baden Ideas
2.38 Frisian Ideas
2.37 Cebu Ideas
2.37 Chachapoyan Ideas
2.37 Moroccan Ideas
2.36 Nivernais Ideas
2.35 Kongolese Ideas
2.35 Telugu Ideas
2.33 Albanian Ideas
2.31 Sienese Ideas
2.30 Pattani Ideas
2.26 Ashikaga Ideas
2.25 Somali Ideas
2.24 Transoxianian Ideas
2.23 Flemish Ideas
2.14 Mahri Ideas
2.06 Cascadian Ideas
2.01 Horde Ideas
2.00 Aymaran Ideas
1.99 Khivan Ideas
1.98 Luzon Ideas
1.93 Luccan Ideas
1.91 Tupi Ideas
1.78 East Frisian Ideas
1.77 Navarran Ideas
1.76 Charruan Ideas
1.74 Andean Ideas
1.69 National Ideas
1.68 Chickasaw Ideas
1.55 Venetian Ideas
1.08 Genoese Ideas
1.07 Kono Ideas
1.04 Madyas Ideas
1.03 Sulawesi Ideas

Identity Issue

So anyway, power level issues can be tweaked by just changing some numbers, no big deal. A much more interesting issue is lack of identity, or what playstyle should you be taking this idea group for?

The algorithm scores ideas for some generic playstyle assumptions. The further your playstyle is from generic, the more it makes sense to pick some idea group that's not generically best.

Some idea groups have great identity. For example it's really clear what Religious is about. It's about spreading your religion, by fighting infidels, and missionary work in your country. Or for a weaker group Trade - it has perfectly fine identity - it's all about making money from trading, and it does exactly what it says.

But for of the ideas have no such identity, and their name usually corresponds to nothing. Like what's "Defensive" ideas about? How is it about defending specifically? Not much at all.

Or how about Diplomatic and Influence? They both give some bonuses to diplomatic stuff, but does it make any sense when you should pick which one? Not really. Or even worse, how about Espionage? It's supposed to be about spies, but spies are not a meaningful EU4 playstyle, it's not CK2. So it's a bag of unrelated bonuses nobody's ever happy about taking. And now that AE reduction got moved from Influence to Espionage, none of Diplomatic/Influence/Espionage trio actually has much identity left.

And the worst of all are idea groups like Maritime, which both lack any sort of identity, and which are painfully weak in every playstyle.

So here's some of my thoughts. What if every idea group was buffed to be playable, and also had some strong identity, so you know that for certain playstyle it actually makes sense to pick it. I grouped them by how well defined they already are.

Idea groups that already work

Administrative

With governing capacity change, it's pretty much a mandatory pick for most playstyles, and doesn't need help.

1.30 weakened its identity. Before that, it was mostly just had coring cost reduction, so if you wanted to play wide (a default playstyle) and expanded mostly by coring, administrative was very good, but not necessary. For tall play, it just didn't do much. Or for expanding by integrating subjects.

It also had state limit increase. Due to the way pre-1.30 trade companies worked, it wasn't really as big a deal as devs wanted, since most of you 0% autonomy land would just belong to a trade company anyway. But state limit also said "take this if you want to play wide".

Now with governing capacity change, wide play makes administrative nearly mandatory, whichever way you expand, but tall play and developing your medium-sized country a lot is also going to run into a lot of governing capacity issues, so administrative are a good idea either way. But they're still especially useful for wide play.

Since administrative ideas are so strong, the best way to improve its identity is not strengthen it, but to give other idea groups some ways to save on governing capacity.

Exploration and Expansion

Back when EU4 was released these two used to have very clear identity. Exploration was about colonizing, especially Americas. Expansion was bout colonizing, especially Africa and Asia.

Back then Exploration had 2 Colonists, perfect for mostly empty America, and gave very good CB on New World pagans, so it was about colonizing there. And Expansion had just 1 Colonist but gave very good CB on Asia and Africa (or whichever parts of Old World you're not based in), so it was about conquering Old World with some colonizing on the side - also perfect match as those lands had a lot fewer uncolonized provinces and a lot more easy pickings of technologically backwards nations.

Somehow second colonist got moved to Expansion, both special CBs got lost (and even the shitty replacement of claim fabrication in trade company regions got removed in 1.30), so they're both really mainly about colonizing the New World, with side serving of the Old.

I think it's best to treat it as a single idea group that just so happens to take two idea group slots. Usually you'll take Exploration as your 1st, Expansion as your 2nd or 3rd.

Taking just one of them really isn't advisable. Maybe Expansion only at 4th or 5th if you want to join colonization late. Or taking Expansion only if you're in Asia and really want to get free Colonialism institution and don't care much about colonists.

So while it would be nice to restore old system where each of them corresponded to part of the world you might want to focus your expansion into, they're good enough as is. And they definitely don't need any buffs, colonists are already one of the best bonuses you can get.

Humanist

Its main selling point is that you don't need to care about peasants' religions, peasants' cultures, and rebellions in general.

From power level point of view, I think it's strictly worse than Religious, since rebels in EU4 are ridiculously weak, so it's no big deal to just crush them whenever they show up. It also lacks amazing Deus Vult from Religious, and you usually only want to take one of the two.

But it definitely saves a lot of rebel fighting micro, so a lot of players love it, and that's clear enough identity.

Religious

It's extremely strong, and has very strong identity - spread your faith by fighting infidels, spread your faith by converting peasants, and have a stable country as result of its religious unity. It doesn't need any help.

Idea groups that just need a little buff

Aristocratic

It's a fairly unfocused bag of bonuses, but I think it can be really good with just a small tweak.

Aristocratic sort of focuses on helping cavalry, but on base level EU4 cavalry is just so awful such bonuses just don't mean much. With no bonuses you should never bother with cavalry. Even with fairly big bonuses cavalry is just barely worth it, and only huge bonus stacking (like going Aristocratic + Tengri + Commonwealth) make it actually good.

If Aristocratic just about tripled its cavalry bonuses, it would gain strong identity without actually making it all that strong. If you take Aristocratic, it would incentivize going from 16inf 4cav 10art armies to 12inf 8cav 10art, or something along those lines, and perhaps even keep that cavalry into late game.

Economic

In principle an idea group saying "play tall" and "earn more money" is fine, but those bonuses are just too low. Especially changing construction costs from -10% to let's say -30% could allow countries to afford all those temples, workshops, and manufactories more easily.

It should probably get bigger development discount as well for playing tall (like -20% to -30%). Various administrative groups are among the strongest, so it needs a big buff to be competitive.

Offensive

Offense primarily means wanting to siege opponent's forts faster, and offensive already does that, but its bonus could be a lot stronger. Doubling down on this, like by adding +1 Leader siege, or +2 max artillery bonus (so you can siege faster, but only if you bring tons of artillery there and pay attrition price) would really help.

I think that paradoxically giving some siege defense would also really help offensively focused countries, as siege racing is how you win fast offensive wars in EU4.

Trade

It's about trade, and gives decent trade bonuses, but it could definitely be stronger.

It could also give big bonuses to trade company provinces - like lower minimum autonomy, lower governing capacity cost, lower trade company investment cost, or such.

If your trade companies had lower governing capacity cost, and were overall more useful, then you could play wide without going administrative - at least as long as you mostly expanded with trade companies, not states.

It could also add some small bonus to trade fleets, like let's say +25% Naval force limit modifier, as trade oriented nations need naval force limit more.

Quality

It has some kind of identity - it wants to make your army stronger per soldier / ship. It just doesn't do enough.

Increasing +0.5 yearly army tradition to like +2 yearly army and +2 yearly navy tradition would greatly round up this idea group, by making not just common soldiers but also army leadership much stronger.

Quantity

It has strong identity - it lets you have bigger army. It's just not clear who would want that. Is it meant for a small country which wants to make its army bigger; or for an already big country like Russia or Ming which wants to make its big army even more enormous?

It needs a buff, and it's actually clear what kind of buff - your huge army will never have enough generals, so like +2 leader limit and maybe a -20% leader recruitment cost discount, will really round it up.

Idea groups that need stronger identity

Defensive

The group claims it's about defending better, but what does that actually mean? EU4 attrition is capped at such a low level, and manpower is so abundant, that there's no hope of ever running the attacker out of manpower by attrition, the way that's totally viable in CK2.

Small bonus to fort defense would actually be far better if you're on the offense. If you're defending, it just delays the inevitable loss slightly. And even if you successfully defend your territory you're still at nearly 0% warscore and with AI unwilling to give you anything for your trouble.

Really the only way this idea group makes any sense is by massively buffing your combat abilities as long as you're on your core territory. It's not exactly an original idea. CK2 "Defensive Pagans" have it. Civ5 Ethiopia has it. So many games have this. I'm surprised EU4 doesn't have anything like that.

Some nations already get +1 naval combat bonus off owned coasts, but there are no bonuses of any kind for land combat on own territory.

-20% Local hostile movement speed would probably do, especially since it stacks with Scortched Earth so well, but it would need to be applied to every province owned by nation with Defensive ideas by an event, so it would be fairly messy to mod.

Without heavy modding, I think +20% movement speed would actually do nicely. It sounds offensive, but actually in EU4 offense is about sieges, and defense is about getting into a advantageous battles to bleed out the attackers. Buffing this weak group with more siege defense and enemy attrition wouldn't hurt either, especially if attrition cap got increased from 5% to something more meaningful like 10%.

Diplomatic

When EU4 came out, Diplomatic used to be a stupidly good idea group. Then it got split into Diplomatic and Influence, nerfed a bunch, and finally some of their bonuses got moved to Espionage to shore that up.

So what Diplomatic / Influence / Espionage each do? They all make your diplomacy betters with a fairly random mix of bonuses each. Fortunately with some simple rearrangement we could give them solid identity.

Let's start with Diplomatic - it will be an idea group for making other countries tolerate your aggressive expansion.

It already has +25% Improve relations, −20% Province warscore cost, Lowered impact on stability from diplomatic actions, and +2 diplomats. All it needs is getting that sweet −20% Aggressive expansion impact from Espionage, and −50% Unjustified demands from Influence.

It could then lose +1 Diplomatic relation or +2 Diplomatic reputation, as these are very strong but don't really fit in its new core identity of helping expand aggressively.

Influence

If Diplomatic is about smoothing out diplomacy for aggressively expanding countries, what should Influence do? Expanding through subjects of course!

First it absolutely needs May fabricate claims for subjects from Espionage, and it could get bigger Diplomatic reputation bonus, and possibly +1 Diplomatic relation if Diplomatic loses it.

−25% Diplomatic annexation cost could be increased to maybe even as much as -50%. Expansion through subjects used to be really effective but now just so much worse than expansion through coring, that we could definitely use a bonus bigger than Administrative ideas' −25% Core-creation cost.

It would be a great pick for a country that has a lot of PUs through missions and no free annexation by button, like Bohemia.

Naval

Naval ideas actually have decent identity - they're about making your navies win battles. It's just that in EU4 this is completely irrelevant 99% of the time, and maybe worth throwing some money at, but definitely not a whole idea group slot.

At the very least it needs to give an extra leader slot or two, so you can actually hire some admirals without starving your land army of leadership (I vaguely recall that next patch is supposed to have separate admiral limit, so that problem might go away).

Even throwing in every single modifier from Naval and Maritime into a single idea group, and then a bit more, would really make a completely underwhelming idea group nobody has any reason to take.

One way to help it would be by increasing importance of naval combat, and removing all straits could do just that, but that would really mess up with AI and overall game balance.

Plutocratic

Plutocratic is a fairly decent but not very coherent group of bonuses for republics (except Noble republics, but they're rare and bad) and also somehow plutocratic monarchies (basically a rare Indian Ocean thing).

Plutocratic could easily become "play a republic" idea group if it had some modest republican tradition bonus like +0.25.

That wouldn't help plutocratic monarchies, but they're weird hybrid already, so that's fine.

Idea groups I don't know what to do about

Espionage

Third "make diplomacy better" group after Diplomatic and Influence, and by far the worst. And I want to make it even worse by moving some of its bonuses to Diplomatic and Influence, as they're close enough to fixable.

The worst thing about Espionage ideas is that EU4's espionage system is just terrible.

Most covert actions unlock really late, and most of them - like Slander Merchants, Support Rebels, or Sabotage Recruitment, are a total waste of time.

Somehow EU3 had a lot better spy system - spies were separate from diplomats, and you needed ideas to get any spies so they could be more powerful. They had abilities such as:

Infiltrate Administration - removes fog of war for a while (it's in EU4 but at adm tech 30 so game never gets there)
Bribe defenders - free siege progress
Commission privateer - creates pirate naval rebels
Support revolt - actually generates rebellion (in 5 different variants) - in early EU4 patches it still sort of worked, by now it's completely useless

And a bunch more.

EU4 really needs drastic changes to spy system for Espionage ideas to do their job. Some ideas:

make Espionage ideas unlock espionage abilities like Infiltrate Administration early
or just make those abilities happen early for everyone
make Support rebels just actually spawn the damn rebels

And it could use some new spy options. Most obvious one would be CK2 style ruler/heir assassinations, but balancing that one looks like hell. Especially if AI starts using it on you.

Some other ideas for new actions:

create royal marriage regardless of target's opinion
if you have royal marriage, give them heir of your own dynasty (or give yourself heir of their dynasty)
steal money (scaling that properly would be difficult)
bribe enemy general to switch to your side
reduce AE with target at price of some gold (like 100 gold and 25 spy points for -10 AE or something)
fabricate other CBs, like Subjugation CB

Unfortunately implementing them in balanced way, especially if they're meant for both player and AI, is not going to be easy.

The easiest way to make Espionage at least a little good would be to make Support rebels actually usable (like +50% monthly rebel tick chance, not +10%, and at far lower money cost, maybe zero, as it's currently ridiculous relative to what you get), make late game covert actions like Infiltrate Administration available earlier, and then increase bonuses for this group anyway.

Innovative

By name this group wants to be about being ahead of everyone else in technology. Except that is just plain impossible in EU4. Especially since they introduced Institutions, the whole world - from Western Europe all the way to African jungle - has the same military technology plus or minus maybe 2 techs (25 years difference), and maybe up to 4 techs (50 years) in adm/dip tech, but those barely make an impact on anything. In reality technology difference between Europe and rest of the world was between centuries (Asia) to thousands of years (Africa and best parts of Americas) to literally tens of thousands of years (Australia and rest of Americas). Especially in ocean going naval technology, Europe was like in a completely different universe compared with what everyone else was doing.

You have no way of getting ahead of the pack, as 10% per year ahead of time penalty is so brutal, even throwing away all awful you can't go more than a few years ahead of everyone else.

Recent patch introduced "innovativeness" mechanic, which is basically a bonus for being ahead of tech, because techs themselves are quite irrelevant. It helps with strategy of going for very high (or even 100%) innovativeness, which is quite achievable for the player as most Western European countries, but totally impossible for the AI.

The whole world has only 302% innovativeness to share between each other, from all techs and ideas, so that's like 1-2% per country. Maybe a bit more as there's events that give innovativeness, and it's possible for multiple countries to gain bonus for the same tech if they get it within 90 days of the leader, but really it's a weird race.

If you don't try to go for max innovativeness, the idea group is really unfocused.

One thing that could work would be reducing ahead of time penalty for techs if you have innovative, so you only pay 5% per year not 10% per year. This cannot be modded directly, so it would need to be a huge list of triggered modifiers based on current year, current tech, and that tech's year. Or the whole "ahead of time" system could be replaced with something less punitive and more dynamic, but the game heavily relies on current system.

Innovative cannot really be saved by just increasing its bonuses. Technology is gained by monarch points, so if we just give Innovative a lot more monarch points - like by huge tech/idea discounts, and advisor cost discounts, then it will be overpowered for everything - while not actually making you take technologies any faster.

Maybe it could increase government reform speed? It's currently painfully slow to get to the good stuff at the end, so it would be one option to do so faster.

Maritime

It's a total dupster fire, even more so than Naval.

It sort of has one use - if you go over force limit on light ships protecting trade, and stack all other naval tradition modifiers to get permanent 100%, you get really huge trade steering bonuses, so your long chain of dominated trade nodes gan give you ridiculous amount of income. Maritime's +100% Naval tradition from protecting trade can actually be quite useful to achieve this, but really if you ever get to this point, then you control half of the world already, so the game is over regardless.

Making it all about trade companies could be a thing, but really Trade already wants those trade company bonuses, and making Maritime "second Trade ideas, just worse" really doesn't seem that appealing.

One way to help it would be to make it "second Trade ideas, except not worse", throwing in some big trade steering and light ship trade power bonuses, maybe an extra merchant, and 5% trade efficiency.

It would probably be better to just remove it from the game completely, and divide its flimsy bonuses between Naval and Trade.

What could have idea group

If we drop Maritime, or just wanted to introduce a completely new group, either as replacement, or an extra, what could that be? Here are a few ideas.

Industry Ideas - give bonuses to goods produced, production efficiency, and development cost. As finisher it lets you change trade goods in a province you own if you develop it enough. So that Napoli at 22dev making crappy Grain? Maybe my throwing some money or points you could change it to Wine or Paper. What about Grain producing mountain in Avellino next door? Maybe deving it up to 20 would flip it to Iron or Copper. The whole system needs to consider terrain, climate, and such things to not do anything crazy, but modest trade good changes wouldn't break the game.

We could even do some limited terrain changes, replacing Forest or Marsh with Farmland, but right now there's not terribly much incentive to do so - it would save you some dev cost, but mostly just remove your defense bonus.

I'm not sure what would be other good idea groups that would fit within framework of the game.