If enemys are already on the left, they usually keep attacking the wall and do not walk around to the right. (from personal experience at least)
No for me it's the opposite the enemies just walk to the right no matter what. The walls on the left just have to be really wide.
(again only from personal experience)
This was if I constructed a wall while enemies were already heading towards that opening. When starting a new round the enemies do walk to the right
I think they look for the least hp between them and the core. I notice they seem to find my thinnest wall. So if I add lots of defense there, they always go there and get annihilated.
