Later game AI is not challenging enough
I am starting to really enjoy my time with 1.2. There is however still an fun killer for me : I strongly feel that past your humble beginnings which may be tough, once you have a stabilized country there is hardly any challenge left in the game.
Even if you neighbor an aggressive empire with 3x your taxe base and manpower, you can probably beat them down easily by just taking advantage of the current AI stupid mistakes.
Disclaimer : I am fully aware that most of us actually do not want an AI that would actually be more competent at the game than we are, or a real challenge that could end your run two centuries into a playthrough, because England/Spain/France/Ottomans got OP and decided to wipe you out. Fair enough.
I still think having the option to face a somewhat competent AI, even if restricted to higher difficulties/talented leaders/historical performers would be great for the game long term.
Country AI
AI seems to be quite bad at optimizing control over its territory, most notably over its capital and governors placement.
IMO should work as follows : every decade, iterate over the top 10 or 20 highest tax base locations. Estimate how much (control x tax base) a governor would yield, assuming maximized proximity (roads and 100% land / 100% naval presence and 100% naval).
If significantly better than current arrangement, establish first governor there, then iterate ton the next one.
Then, over the course of the decade, really focus on pushing roads and land / maritime presence and naval accordingly.
Army AI
- Always consolidate to frontage max + reserves in safe territory. This should apply to alliances as well (HRE shenanigans feeding their small stacks)
- if enemy has significant hidden forces and you have enough on your own, a reserve stack should be kept within a few days of the one leading an objective (like a siege).
- consider the potential of enemy reinforcements before picking an "easy" battle on a disadvantageous location, especially if enemy could have hidden forces in adjacent locations.
- if on a defensive war, especially against a strong enemy, you should remain defensive on defensible locations and not venture where an hidden army could catch you in a bad spot.
- if caught on a loosing battle / threatened by one by an approaching army, immediately retreat to the best position you can. Dont wait for your stack to be wiped out.
- naval invasions should never be attempted if you don't have both naval superiority AND a safe landing area (port you own/allied, protected by a fort or a significant force, or ability to land a full stack in one go).
Landing forces should be consolidated to full stacks before starting to venture into enemy territory.
- never resort to carpet siege AI unless enemy is utterly wiped out/entirely visible on the map.
PS : I'd be very interested to know if some of these behaviors could be moddable. From my understanding, you can only mod the weights of some AI actions (the "defines" file) but can not change overall behavior.