I know D:OS 2 calls for a non linear adventure, but honestly, I'm puzzled by the whole Arx act. I've been running through the game no problem, but Arx has a lot of quest that seem to be able to end up abruptly, and definitely not giving the same amount of XP depending on what you choose. I get that, but the gaps are horrific. (The doctor : ~1 million XP if you do it all, in my case apparently around 30K and no possibility to enter the house anymore).
A lot of quest go this way. I think there are ways to amount the XP needed until Arx where I assume the point is to arrive pretty much at 20. The quests are intertwined with each other, not very clear, and to be fair I ended up going in circles a lot, wondering what I should do next.
Worse part is that I read that you could enter the doctor's house for example but that you need an item from Act 2. Always a good design pattern to lock a good chunk of the game behind possible missing things...
In short, Arx could still use some redesign it seems (oh yeah, I know it's too late... Still...)