I don’t know if the game has really gotten harder, but I’m definitely finding I can’t be as lazy as I have been previously.
Playing Vicky, Immortal, Large Continent or Small Continent maps, I’d previously found I could start with a Scout and get out two Settlers early and often still get a Wonder like ToA. That would somewhat depend on early diplomacy and friendships and terrain, and yeah sometimes I’d have to rein that in a bit (eg weaker start, aggressive AI). I could also usually hit an AI neighbour pretty hard if I needed to, but really needed Iron or Horses to make that stick.
I’m finding the AI players are now more dangerous early game, more aggressive, more forward settling, and I have to be more willing to get out early military rather than just settlers and builders. The AI on higher difficulties can really pump out ranged units, tear through walls, and capture cities - indeed, capturing a city and holding it can be tricky without careful planning, because without walls (given you’ve likely just demolished them) and being in the middle of you enemy’s empire the AI is quite capable of recapturing cities if you don’t have sufficient units to hold it. Attacking the AI requires much more discipline - the AI can get dug in like a tick with walls and ranged units, and it uses units better (although I can’t put my finger on what exactly it’s doing differently). City States joining the fray and Medieval Emergencies are also more of a factor. Early wonders are far more competitive.
Man, I love it. More please.
It’s also clearly not just about the AI being better. The changes to resources, Cav and Rams, buffs to walls, and even map generation (eg terrain seems more tactically significant to wars given how mountains are generated) have also made things tougher. I think the production boosts may have also helped the AI quite a bit, although it’s hard to say. Grievances are also more of an issue - before, everyone basically ignored early war, whereas now Civs can get quite upset initially although the Grievances wear off more quickly early.
I haven’t had a chance to play a game through past Medieval, so I can’t comment on mid to late game. The AI seems to still have problems with upgrading units (whereas City States don’t seem to have the same issues). I think I can also still bully the AI if I really lean into science and military eg campus spam, aggressive chopping, but hey that’s not fun.