The standard english dictionary translation of 奥 is "interior" or "inner part". Being literal minded, I have had a hard time getting my head around its usage in a game I am playing.
As context, there are two buildings on opposite sides of the map, the mansion being on the west and the church on the east. There is a boundary wall furthest west (further than the mansion) and another furthest east (further than the church). The 「奥の壁」is not referring to the walls of the church (which is what I would expect), but the boundary wall slightly east.
I checked Kotobank and I think I got the gist, but I am not skilled enough to understand or translate the definition accurately:
So, my vague understanding is that 奥 here actually refers to an entrance that leads to a wider open area, in this case the outside, rather than the interior (of the church, which is smaller)?