Hello
Is it me or the difficulty you choose doesn't really matter ?
I'm used to play civilization but I never played endless legend and it's my 2nd evening on the game so I still have a lot to learn... but I'm already crushing the "serious" AI like it's nothing, I took almost all my continent, the AI doesn't seem to know how to develop quickly nor how to fight (you just have to take the cliff and they will suicide on you).
I think part of the issue also comes from the neolithic era, when you can multiply way too easy if you split while the AI tend to stay packed.
So after 25-30 turns the game is already over :


Even the AI on other continent (2nd to 4th) which I can't bully get quickly behind.
After that I just have to ransack outposts/cities one by one and crush some troops along the way... (the gap only widens)

It will be difficult to test the balance and the gameplay if the AI don't bring any resistance ^^