Add option during game setup: Robber automatically returns to the desert after the person who placed the robber rolls the dice again. i.e., players A,B,C,D - A rolls a 7 (or plays a knight card) and places the robber. B, C, D roll non-7 and nobody plays a knight card. After A rolls dice again, robber goes back to the desert. If B, C, D roll a 7 or play a knight card, robber doesn't return until that player rolls again.