I've been having intermittent movement bugs over the past week...
I'll hold down RMB but my dude won't budge. :(
I did a little testing just now, and found that it wasn't the code that was bugged... it's my mouse! Unless I apply a good deal of force to my right mouse button, the "pressed" state flickers on and off.
It helped that the graphics were so primitive. Lots of imagination required. But yeah, I loved seeing the little farmers leave footprints of mud as they went upstairs for grog - and the cats hunting pests in abandoned tombs.