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