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