Here is the full list of all 15 SPLIT BULLET achievements.
Get killed for 10 times, with the record of 90%
Defeat 'Reverse'
Defeat every stages
Defeat 'Space'
Defeat 'Time'
Defeat 'Surface'
Defeat 'Twins'
Defeat 'Geometry'
Get killed for 10 times
Defeat 'Trianglism'
Defeat 'Hyper Spin'
Defeat 'Hexagonal'
Get killed for the first time
Defeat 'Bad Squares'
Run the game for the first time