A neat little experiment in meaningful NPC interactions was Siboot[1]. The DOS version is probably available somewhere. It's rock-paper-scissors with a social element. Well worth at least an evening's play. The author has released the mac source-code, but good luck building it. The DOS version is available at various abandonware sites and that's probably the easiest way to play it.

1: https://en.wikipedia.org/wiki/Trust_%26_Betrayal:_The_Legacy...