Here is the full list of all 21 DeathMetal achievements.
Collected smaller paddle malus 10x.
Collected tiny balls malus 10x.
Collected high speed malus 10x.
Finished Level #10 in Episode 3.
Unlocked Episode 4.
Unlocked Episode 3.
Played with 4 balls at once.
Collected extra life bonus 10x.
Collected 100 bonuses total.
Collected fire bonus 10x.
Collected bigger paddle bonus 10x.
Collected magnetic bonus 10x.
Collected big balls bonus 10x.
Unlocked Episode 2.
Collected split ball bonus 10x.
Finished first level!
Collected slow speed bonus 10x.
Played with 6 balls at once.
Finished Level #10 in Episode 1.
Finished Level #10 in Episode 2.
Finished Level #10 in Episode 4.