Here is the full list of all 23 Moonchild achievements.
All quests completed
100,000 gold coins
Calypso - 1000 kills
Calypso - Lv 50
Om - 666 kills
Susanna - 200 magic kills
30 creatures summoned
Talk 16 times
Jardel - 100 magic kills
Jardel - 100 kills
Stardust - 100 kills
16 hours played
Om - 100 kills
Susanna - 100 kills
Dabbabbu - 100 kills
Rupert - 100 kills
Gabriel - 100 kills
5 quests completed
10,000 gold coins
Kenneth - 100 kills
Calypso - 100 kills
2,500 gold coins
1 hour played