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