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