Here is the full list of all 20 Neoncube achievements.
Click on the only off-grid block in the game
Play levels 1-10 without dying
Play levels 11-20 without dying
Play levels 21-30 without dying
Play levels 31-40 without dying
Play levels 41-50 without dying
Play all 50 Levels in one session
Die 1000 times
Break 100 times
Fall into lava 100 times
Get blown up 100 times
Kill the first Boss
Kill the second boss
Kill the third boss
Kill the fourth boss
Kill the final boss
Jump 10000 times
Use cheats
Use a well known code
Find a secret in the multiplayer lobby