Fun little game, saw it from Idle Cub on Youtube.
I genuinely believe it has potential to be turned into a fleshed out indie game because the different concepts like digging and tower defense had been beautifully integrated.
Extra features, perhaps random rare ore used for other types of towers.
Thanks for the feedback. It does seem like there might be interest. Just working on how to flesh it out.
Some thoughts about making the digging a bit more interesting:
1. Add different types of rocks. As you move further away from the center they get harder.
2. Should the player be able to see the entire grid, or just a number of squares away from where they have already dug?