Crop Dungeons

[Ants]

In Rune Factory 4, you could plant dungeon seeds and grow dungeons with difficulty that scaled with the seed level. I think it was a cute mechanic.
http://kaze-no-travelers.tumblr.com/pos ... is-area-in

You should really play rune factory sometimes, it's a fun series.

[Lunarius_Haberdash]

And here I thought you were going to suggest something interesting, like wild Wickermen dungeons in fields of wild barley.

[Luanes]

Maybe something like every "grid" could have a "secret" dungeon or localized resource based upon some specific trees / crops distribuition. So, for unlocking those, it would need to "plant" more over the walls