I've added bandits, which move around and shoot you. I'll probably upgrade their behaviour to include also "peaceful" behaviour; i.e., they might be sitting in the grass smoking cigarettes until you get near, or they should sleep at night, or even at random hours, or just stand around staring at stuff. At any rate, it's good for now.
I feel I've gained some real momentum over the past week or two. Today I'm adding some more enemies, a ghost that latches on to you and probably a zombie/mummy cross enemy that follows you with it's arms out (it will be the only enemy with arms, if indeed I decide to give it arms) and takes a lot of hits to kill.