How much depth is there to the NPC interaction?

Really a lot! We have more than 1000 NPCs. Every single NPC has it’s own work to do over the day, has social contacts and reacts on changing game situations. I will give you an example:

Family Smith is sitting next to the camp fire of their enclave in the morning. They have breakfast together.

If you talk to them father Smith will tell that he’s in a bad mood, because he has to hack wood today. And after that he has a long walk to the next village to get some fresh water. Mother Smith will tell you that she’s always worried when her son Timmy goes playing at the junkyard. And she’s also worried when her husband to travel to Dustville to get some fresh water (ironic, he? ).

This afternoon it’s time again. If you talk to Timmy he will tell you that he's excited, because he will meet Sara at the junkyard today. They want to play the “Seeker Game”. Father is finished his breakfast first and leaves to get his axe. He has a lot to do today. If you talk to him know, he starts swearing, he really hates hacking wood.

After mother Smith and Timmy finished their breakfast the kid leaves to the junkyard, the mother goes home to get her gun. She has to go hunting today.

To shorten this whole thing: Father Smith will travel to Dustville later today. There he gets some water, but that’s not the only thing he gets. We can only guess what he’s doing in her house… Mother Smith shoots a bear and guts it to get some flesh. And she make a necklace out of the teeth in the afternoon. Timmy plays with Sara at the junkyard till the evening. If you talk to him he asks you to play with them the “Seeker Game”. In the evening the whole family meets at the camp fire again. They listen to Bog who’s playing the guitar. And when they get tired they go sleeping.

Imagine this with more than 1000 NPCs and you can guess how alive the world of The Fall is.