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