Here is the full list of all 63 FLATLAND Vol.1 achievements.
Die for the first time
Die 10 Times
Die 30 Times
Die 50 Times
Die 100 Times
Die 200 Times
Complete normal mode
Complete Faster than Light mode
Complete Not Him Again mode
Unlock Faster Than Light mode
Unlock Not Him Again mode
Unlock Square Fights Back
Collect cube
Collect all cubes