Here is the full list of all 25 Hexterio achievements.
Completed Level 1-5
Completed Level 1-9
Completed Level 1-11
Completed Level 1-12
Completed Level 2-6
Completed Level 2-9
Completed Level 2-10
Completed Level 2-12
Completed Level 3-9
Completed Level 3-12
Completed Level 4-4
Completed Level 4-9
Completed Level 4-12
Completed Level 5-6
Completed Level 5-7
Completed Level 5-8
Completed Level 5-10
Completed Level 5-11
Completed Level 5-12
Completed all levels in Mode 1
Completed all levels in Mode 2
Completed all levels in Mode 3
Completed all levels in Mode 4
Completed all levels in Mode 5
Completed all levels in the game