Here is the full list of all 13 Antithesis achievements.
You beat the easy level!
You beat the medium level!
You beat the hard level!
You beat the impossible level! :O
You destroyed 50 asteroids!
You destroyed 150 asteroids!
You destroyed 300 asteroids!
You picked up 10 powerups!
You picked up 25 powerups!
You picked up 50 powerups!
You reached a score of 3000!
You reached a score of 5000!
You reached a score of 6500!