Mine Your Way Out - Escape a pixelated underground

General feedback about the games progression would be helpful.

Game length: ~50 minutes + 2 minutes it takes to generate a world

The game is about mining resources to escape the underground. The world is made up of millions of pixels that you can break with various tools. You start out slow but later in the game you will cause some major destruction.

You can play the game here (Newgrounds account required): https://www.newgrounds.com/portal/view/894860

Don't play on Firefox it's laggy