Here is the full list of all 15 Betrix achievements.
Clear 200 lines
Clear 2000 lines
Clear lines by quad 20 times
Clear lines by quad 200 times
Special Clear 20 lines
Special Clear 200 lines
All clear 10
All Clear 100
1 level completed
10 levels completed
Play Classic levels 10 times
follow the rhythm 200 times
follow the rhythm 2000 times
Create you own level
Complete a level without a single miss