Here is the full list of all 15 Little Cells achievements.
Detonate 5 White cells
Play 10 games
Clear the screen 5 times in a single game
Kill 0000FF Blue cells
Create 10 Grey cells in a single game
Read the whole tutorial and full credits
Lose a game with 5 White cells in stock
Reach a x9 multiplier 5 times during a single game
Play 100 games
Reach 9 000 points in a single game
Score 5000 points between two White cell uses
Kill 1974 Dark cells
Create 1954 White cells
Accumulate 180 000 points
End a game with at least 1978 points without creating a single Grey cell