Here is the full list of all 21 Bit Heroes achievements.
Reach Level 50
Reach Level 100
Reach Level 200
Collect 20 Different Familiars
Collect 50 Different Familiars
Collect 100 Different Familiars
Defeat Gemm
Defeat Quirrel
Defeat Kov'alg
Collect 15 Quest Stars
Collect 30 Quest Stars
Collect 50 Quest Stars
Reach Level 20
Collect 5 Different Familiars
Make a fusion
Defeat Lord Cerulean
Collect 5 Quest Stars
Add a friend
Join a Guild
Reach Level 5
Collect 1 Familiar