Tunnel warfare is well documented and was definitely a thing. I imagine it being used at most big sieges.
And those big thick walls that we’ve seen in the trailer would be ideal for such a feature. Could be something similar to petards.
I wonder how more powerful are those walls going to be compared to the previous age games.
It had always been an annoyance that they were working more like a fench that could be destroyed fairly easy even by foot soldiers and that you could also shot through them. Hope it’s going to be different now. AOE 4 ideas