The game isn't ours

I start off by writing an informal Disclaimer.
Mabinogi ("The Game") isn't ours and copyright is owned by Nexon.

We are just creating a server as exercise and practive of our art.
All content our servers provide is custom written by us, any resemblances are purely coincidental.

Why custom quests and NPCs

This is a simple answer. It is simply that all NPCs and quests fall under copyright law, and thus we will and cannot copy them.