dig

Digging a hole

Obtained by digging 1 hole.

Master of digging

Obtained by digging 5 holes.

I am become death

Obtained by digging 10 holes. (This one wasn't given to me until I closed the game)

I shall not pass

Launch the game 1 week after last playing it. Similar to The Stanley Parable 'Go Outside' achievement, just shorter.
I think setting your system clock ahead 1 week would count as cheating for this, as it does for The Stanley Parable, so don't do that even though folks on Steam forums suggest it.