Here is the full list of all 29 Reverse Defenders achievements.
I've cleared stage 3.
I've cleared stage 2.
I've shifted World Lines.
I've cleared stage 1.
I've cleared Tutorial
Saved the world within eight world line shifts.
Saved the world within nine world line shifts.
Cleared all stages.
A mysterious stick figure told me the secrets of the world.
Collected all the classes.
Got all the red treasure chests.
I got the red treasure chest.
Got all the stars.
I flew pretty far on the knockback.
I flew a lot on the knockback.
Knocked it back and let it fly there.
I've done extra heavy damage with poison.
I've done big damage with poison.
I've mastered Soul Eater.
First time using Soul Eater.
I did 50000 damage.
I did 30000 damage.
I did 10000 damage.
I did 5000 damage.
I did 1000 damage.
I've shifted the World Lines ten times.
I've cleared stage 6.
I've cleared stage 5.
I've cleared stage 4.