Hi, thanks for playing the game! Reposting from the main game page:
As the preggopixels game jam deadline ends tomorrow, stages that are unfinished have had to be cut from the release build in favor of polishing off things that are actually in game. The lever mentioned by NPCs can't be purchased yet, as its only purpose is to open up the next zone of the game. Other NPCs should have a few more dialogue trees, depending on how many times you've met them/whether or not you're pregnant. But if you want to head down to the mines you'll just have to stay tuned with development!
Progress on the mines stage has been coming along nicely but, it still requires a great deal more work + new slates of enemies to fill it out. Far more than is going to be met before the deadline.