Here is the full list of all 38 Skilltree Saga achievements.
Learn 20 Skills
Login 20 times
Defeat 25 Orc Scouts.
Defeat 100 enemies without dying or fleeing
Defeat 75 enemies without dying or fleeing
Defeat 25 Orc Wolves
Login 10 times
Defeat 10 Orc Scouts.
Defeat 10 Frost Wolves
Defeat 50 enemies without dying or fleeing
Defeat 3 Orc Scouts.
Defeat 10 Orc Wolves
Defeat 3 Orc Wolves
Defeat 25 bosses
Defeat 25 Goblin scouts
Loot 5000 ducats from defeated enemies
Learn 10 Skills
Defeat 10 Goblin scouts
Defeat 200 enemies
Loot 2500 ducats from defeated enemies
Defeat 10 bosses
Defeat 3 Goblin scouts
Login for the first time
Defeat 25 enemies without dying or fleeing
Defeat 3 Frost Wolves
Defeat 5 bosses
Defeat 100 enemies
Loot 1000 ducats from defeated enemies
Defeat 2 bosses
Defeat 10 enemies without dying or fleeing
Defeat 50 enemies
Defeat 10 Forest Mushrooms
Loot 250 ducats from defeated enemies
Defeat 10 Mosquitos
Defeat 3 Forest Mushrooms
Defeat 10 enemies
Learn 3 Skills
Defeat 3 Mosquitos