Here is the full list of all 11 Down The Hole achievements.
Click the start button on the menu
Play a user made level
Destroy 1,000 turrets
Bounce on the jump pads 1,000 times. I'm sure they are fun!
Dang, you really went that fast?
Publish a level to the workshop
Unlock Chapter 2
Unlock Chapter 3
Unlock Chapter 4
Unlock Chapter 5
You found the hidden cube!