Here is the full list of all 21 Cubicity achievements.
Obtain all the Achievements in-game
Win level 4, in world 1, without holding any object
Beat level 11, In world 3, By casting only 1 portal
Beat level 3, In world 2, by casting only 1 portal
Beat level 2, In world 4 unofficially (w)
Change 6 cubes into magnetic cube
Merge 11 objects
Find the evil scientist portrait
Find our logo
Get to Egypt
Let seamus get bored
Win level without casting magnet
Get to 10 hp without dying !
Let the cubes fly!
Win level without holding object
Obtain a New Weapon
Stuck in level for 5 minutes
Hold 8 cubes at the same time
Cast magnet 25 times in one level
Get stuck on a level
Launched Cubicity for the first time