This reminded me of Lemmings in all the best ways. Very impressive and polished for a jam game. Nice job!
I do agree with what someone else said about the speed of the bottys. It would feel a bit nicer if it was faster, however I understand this could also result in difficulties for the player at points so it may be better to leave it as is.
PS: Am very curious about how you approached the digging mechanic and will be sure to take a look through your source code. Thanks for sharing it!