Here is the full list of all 14 Radon Break achievements.
Reach 100k points
Reach 250k points
Reach 500k points
5 balls on the screen at the same time
10 balls on the screen at the same time
Reach stage 10
Reach stage 20
Reach stage 30
Reach stage 40
Skip 1 stage by collecting "Next Stage" item
Stick 3 or more balls on your paddle
Get largest paddle size
Get smallest paddle size
Get all achievements