UPDATE: Dialogue System
Well, this is just the result in my spare time...
Introducing the "Dynamic NPC" system which will make NPCs talk first when player approaches. I brought this from The Elder Scroll, which NPCs will notice the player and act several things but mostly saying hello to player.
And with this, the NPCs won't be introvert :p
This implementation will be added in next release, though.
Here is the screenshots in development phase.