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