Here is the full list of all 16 Amaranthine achievements.
Complete game on normal
Destroy 5000 enemies
Destroy 12 cargo ships in a single run
Complete level without taking any damage
Ram 50 enemies
Destroy the battlecruiser
Destroy the bomb
Kill 10 enemies in 1 secon
Destroy 1000 enemies
Destroy the overwatcher
Destroy 250 enemies
Sell 100 weapons
Complete subwarp level
Find legendary weapon
Complete game on legend mode
Reach 20 level on legend mode