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
Reach Level 50
Collect 20 Different Familiars
Defeat Gemm
Collect 15 Quest Stars
Make a fusion
Collect 5 Different Familiars
Reach Level 20
Defeat Lord Cerulean
Collect 5 Quest Stars
Join a Guild
Reach Level 5
Add a friend
Collect 1 Familiar