NPCs and a bridge

I have given the two essential NPCs a role in the game (Dave Daredevil
and Bill the Builder) and I have also implemented the basics of the
second puzzle which involves messing with time to get a bridge over a
river built.

To progress you must now do certain tasks for the NPCs to progress in
the game. I’m Also thinking about altering Dave’s task so as to make
the game more diverse.