Cool game! Having a leaderboard for competition is also a great way to keep people invested.
My only big critique is that the level generation was not balanced. I would have levels where I could walk straight to the exit, while other levels would require building three bridges to get the pickaxe and then sprinting to the opposite edge of the map to open the exit. Also, a tree would sometimes overlap with a boulder, making me think I could reach the exit when I could not.
The retro art style is really nice, but the screen can feel cluttered, and it's weird that the pickaxe is not revealed at the very start of a level.
Other than these things, this is a pretty cool game! GL!