This was really cool!
I'd love a full game of this!
I would love a way to reach diagonals though. If not to mine it (fair enough) then at least mark them as a bomb.
Maybe an item could mine at a distance? So we can clear those little areas that are surrounded by bombs?
Or perhaps an item (expensive?) that lets us pass through a marked bomb without mining it to prevent impassable areas?
Just some ideas, but I'm looking forward to the full game. I've added it to my Steam wishlist!