Getting more and more items as you progress through the day is great. I loved the different options and spamming tools up and down the caves. Also, the soundtrack is great, i was perfectly in the "mining" mood.

I did find myself spamming the same 2 tools (cart and pickaxe) and rarely anything else though.
I also found it a bit frustrating that you could not send more than one tool after the other (cart immediately after pickaxe for example). However, I realize that you'd have to program a sort of cooldown or the cave would be cleared extremely fast... 
In any case, I loved it! Very nice submission :)

First and foremost, is the title a Steely Dan reference? I really enjoyed this even though I sucked at it. Eventually got into a bit of a groove switching my tools and zooming up and down trying to keep each row occupied. Obviously this would have been out of scope for a jam, and sort of goes against the design element of things ramping up more and more, but I was wishing I could buy something that could be placed and auto-shoot certain projectiles on a row, or get the ability to chain shots, so like shoot the pickaxe and that automatically shoots a cart right behind it.

This is a neat game. I like how hectic it gets the longer you play. Good job!